eclipse won't load workspace - eclipse

Question

I was working in eclipse, and it got stuck, and next it refused to load my usual workspace folder
this is what the logfile shows
how can i load this folder again?
!SESSION 2013-08-21 14:27:21.896 -----------------------------------------------
eclipse.buildId=M20130204-1200
java.version=1.7.0_25
java.vendor=Oracle Corporation
BootLoader constants: OS=win32, ARCH=x86_64, WS=win32, NL=en_US
Framework arguments: -product org.eclipse.epp.package.java.product
Command-line arguments: -os win32 -ws win32 -arch x86_64 -product org.eclipse.epp.package.java.product
This is a continuation of log file C:\Dev\workspace\.metadata\.bak_0.log
Created Time: 2013-08-21 14:27:29.774
!ENTRY org.eclipse.ui 4 0 2013-08-21 14:27:29.774
!MESSAGE Error occurred during status handling
!STACK 0
java.lang.NullPointerException
at org.eclipse.ui.internal.statushandlers.StatusHandlerRegistry.<init>(StatusHandlerRegistry.java:72)
at org.eclipse.ui.internal.statushandlers.StatusHandlerRegistry.getDefault(StatusHandlerRegistry.java:91)
at org.eclipse.ui.statushandlers.StatusManager.getStatusHandler(StatusManager.java:135)
at org.eclipse.ui.statushandlers.StatusManager.handle(StatusManager.java:189)
at org.eclipse.ui.statushandlers.StatusManager.handle(StatusManager.java:231)
at org.eclipse.ui.statushandlers.StatusManager$StatusManagerLogListener.logging(StatusManager.java:305)
at org.eclipse.core.internal.runtime.RuntimeLog.logToListeners(RuntimeLog.java:160)
at org.eclipse.core.internal.runtime.PlatformLogWriter.logged(PlatformLogWriter.java:100)
at org.eclipse.equinox.log.internal.ExtendedLogReaderServiceFactory.safeLogged(ExtendedLogReaderServiceFactory.java:86)
at org.eclipse.equinox.log.internal.ExtendedLogReaderServiceFactory.logPrivileged(ExtendedLogReaderServiceFactory.java:205)
at org.eclipse.equinox.log.internal.ExtendedLogReaderServiceFactory.log(ExtendedLogReaderServiceFactory.java:178)
at org.eclipse.equinox.log.internal.ExtendedLogServiceFactory.log(ExtendedLogServiceFactory.java:65)
at org.eclipse.equinox.log.internal.ExtendedLogServiceImpl.log(ExtendedLogServiceImpl.java:87)
at org.eclipse.equinox.log.internal.LoggerImpl.log(LoggerImpl.java:54)
at org.eclipse.core.internal.runtime.PlatformLogWriter.logging(PlatformLogWriter.java:43)
at org.eclipse.core.internal.runtime.RuntimeLog.log(RuntimeLog.java:96)
at org.eclipse.core.runtime.SafeRunner.handleException(SafeRunner.java:71)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:44)
at org.eclipse.ui.internal.Workbench$54.run(Workbench.java:2412)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
!ENTRY org.eclipse.ui 4 4 2013-08-21 14:27:29.789
!MESSAGE Unhandled Exception
!ENTRY org.eclipse.ui 4 4 2013-08-21 14:27:29.789
!MESSAGE Unhandled Exception
!ENTRY org.eclipse.ui 4 0 2013-08-21 14:27:29.789
!MESSAGE Error occurred during status handling
!STACK 0
java.lang.NullPointerException
at org.eclipse.ui.internal.statushandlers.StatusHandlerRegistry.<init>(StatusHandlerRegistry.java:72)
at org.eclipse.ui.internal.statushandlers.StatusHandlerRegistry.getDefault(StatusHandlerRegistry.java:91)
at org.eclipse.ui.statushandlers.StatusManager.getStatusHandler(StatusManager.java:135)
at org.eclipse.ui.statushandlers.StatusManager.handle(StatusManager.java:189)
at org.eclipse.ui.statushandlers.StatusManager.handle(StatusManager.java:231)
at org.eclipse.ui.statushandlers.StatusManager$StatusManagerLogListener.logging(StatusManager.java:305)
at org.eclipse.core.internal.runtime.RuntimeLog.logToListeners(RuntimeLog.java:160)
at org.eclipse.core.internal.runtime.PlatformLogWriter.logged(PlatformLogWriter.java:100)
at org.eclipse.equinox.log.internal.ExtendedLogReaderServiceFactory.safeLogged(ExtendedLogReaderServiceFactory.java:86)
at org.eclipse.equinox.log.internal.ExtendedLogReaderServiceFactory.logPrivileged(ExtendedLogReaderServiceFactory.java:205)
at org.eclipse.equinox.log.internal.ExtendedLogReaderServiceFactory.log(ExtendedLogReaderServiceFactory.java:178)
at org.eclipse.equinox.log.internal.ExtendedLogServiceFactory.log(ExtendedLogServiceFactory.java:65)
at org.eclipse.equinox.log.internal.ExtendedLogServiceImpl.log(ExtendedLogServiceImpl.java:87)
at org.eclipse.equinox.log.internal.LoggerImpl.log(LoggerImpl.java:54)
at org.eclipse.core.internal.runtime.Log.log(Log.java:62)
at org.eclipse.ui.internal.WorkbenchPlugin.log(WorkbenchPlugin.java:809)
at org.eclipse.ui.internal.EarlyStartupRunnable.handleException(EarlyStartupRunnable.java:81)
at org.eclipse.core.runtime.SafeRunner.handleException(SafeRunner.java:75)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:44)
at org.eclipse.ui.internal.Workbench$54.run(Workbench.java:2412)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
!ENTRY org.eclipse.mylyn.tasks.ui 4 0 2013-08-21 14:27:29.789
!MESSAGE Unable to execute early startup code for an extension
!STACK 1
org.eclipse.core.runtime.CoreException: Plug-in org.eclipse.mylyn.tasks.ui was unable to load class org.eclipse.mylyn.internal.tasks.ui.TasksUiPlugin$TasksUiStartup.
at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.throwException(RegistryStrategyOSGI.java:194)
at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.createExecutableExtension(RegistryStrategyOSGI.java:176)
at org.eclipse.core.internal.registry.ExtensionRegistry.createExecutableExtension(ExtensionRegistry.java:905)
at org.eclipse.core.internal.registry.ConfigurationElement.createExecutableExtension(ConfigurationElement.java:243)
at org.eclipse.core.internal.registry.ConfigurationElementHandle.createExecutableExtension(ConfigurationElementHandle.java:55)
at org.eclipse.ui.internal.WorkbenchPlugin$1.run(WorkbenchPlugin.java:273)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:52)
at org.eclipse.ui.internal.WorkbenchPlugin.createExtension(WorkbenchPlugin.java:269)
at org.eclipse.ui.internal.EarlyStartupRunnable.getExecutableExtension(EarlyStartupRunnable.java:117)
at org.eclipse.ui.internal.EarlyStartupRunnable.run(EarlyStartupRunnable.java:66)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.ui.internal.Workbench$54.run(Workbench.java:2412)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:53)
Caused by: org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter$TerminatingClassNotFoundException: An error occurred while automatically activating bundle org.eclipse.mylyn.tasks.ui (288).
at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:469)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:216)
at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:395)
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:464)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(Unknown Source)
at org.eclipse.osgi.internal.loader.BundleLoader.loadClass(BundleLoader.java:340)
at org.eclipse.osgi.framework.internal.core.BundleHost.loadClass(BundleHost.java:229)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadClass(AbstractBundle.java:1212)
at org.eclipse.core.internal.registry.osgi.RegistryStrategyOSGI.createExecutableExtension(RegistryStrategyOSGI.java:174)
... 11 more
Caused by: org.osgi.framework.BundleException: The activator org.eclipse.mylyn.internal.tasks.ui.TasksUiPlugin for bundle org.eclipse.mylyn.tasks.ui is invalid
at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:172)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:679)
at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:381)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:300)
at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:440)
at org.eclipse.osgi.internal.loader.BundleLoader.setLazyTrigger(BundleLoader.java:263)
at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
... 23 more
Caused by: java.lang.NoClassDefFoundError: org/eclipse/mylyn/monitor/ui/IUserAttentionListener
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
at java.lang.Class.getConstructor0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.loadBundleActivator(AbstractBundle.java:167)
... 29 more
Caused by: org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter$TerminatingClassNotFoundException: An error occurred while automatically activating bundle org.eclipse.mylyn.monitor.ui (281).
at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:122)
at org.eclipse.osgi.baseadaptor.loader.ClasspathManager.findLocalClass(ClasspathManager.java:469)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.findLocalClass(DefaultClassLoader.java:216)
at org.eclipse.osgi.internal.loader.BundleLoader.findLocalClass(BundleLoader.java:395)
at org.eclipse.osgi.internal.loader.SingleSourcePackage.loadClass(SingleSourcePackage.java:35)
at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:461)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:421)
at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:412)
at org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader.loadClass(DefaultClassLoader.java:107)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 34 more
Caused by: org.osgi.framework.BundleException: Exception in org.eclipse.mylyn.internal.monitor.ui.MonitorUiPlugin.start() of bundle org.eclipse.mylyn.monitor.ui.
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:734)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.start(BundleContextImpl.java:683)
at org.eclipse.osgi.framework.internal.core.BundleHost.startWorker(BundleHost.java:381)
at org.eclipse.osgi.framework.internal.core.AbstractBundle.start(AbstractBundle.java:300)
at org.eclipse.osgi.framework.util.SecureAction.start(SecureAction.java:440)
at org.eclipse.osgi.internal.loader.BundleLoader.setLazyTrigger(BundleLoader.java:263)
at org.eclipse.core.runtime.internal.adaptor.EclipseLazyStarter.postFindLocalClass(EclipseLazyStarter.java:107)
... 43 more
Caused by: org.eclipse.swt.SWTException: Device is disposed
at org.eclipse.swt.SWT.error(SWT.java:4361)
at org.eclipse.swt.SWT.error(SWT.java:4276)
at org.eclipse.swt.SWT.error(SWT.java:4247)
at org.eclipse.swt.widgets.Display.error(Display.java:1258)
at org.eclipse.swt.widgets.Display.asyncExec(Display.java:709)
at org.eclipse.mylyn.internal.monitor.ui.MonitorUiPlugin.start(MonitorUiPlugin.java:145)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl$1.run(BundleContextImpl.java:711)
at java.security.AccessController.doPrivileged(Native Method)
at org.eclipse.osgi.framework.internal.core.BundleContextImpl.startActivator(BundleContextImpl.java:702)
... 49 more

Answer 1

I had the same problem.
Deleting .metadata/.plugins/org.eclipse.e4.workbench/workbench.xmi worked. I am not sure of the root cause, though.
OR
Move the contents of "plugins" folder to some other folder and restart eclipse. Eclipse will add all these plugins after restart. Replace the new folders with the copied folders.

Answer 2

Removing the .snap file worked for me:
rm WORKSPACE/.metadata/.plugins/org.eclipse.core.resources/.snap

Answer 3

Just linking the solution provided by Fredrik in the thread: eclipse won't start but no error is shown
"It seems to fail when trying to restore the workspace.
Try:
Open a new workspace. If it has been set to use a default, go to \configuration.settings\org.eclipse.ui.ide.prefs and set SHOW_WORKSPACE_SELECTION_DIALOG to true
Try deleting /.metadata/.plugins/org.eclipse.core.resources/.snap
As suggested in a comment: If using Eclipse 4, you may have to delete the file .metadata/.plugins/org.eclipse.e4.workbench/workbench.xmi aswell."