webcam + external camera failure, cannot access /dev/video*: No such file or directory - ubuntu-16.04

Question

I hope someone out there can help me!
I'm working on a Toshiba SATELLITE-L50-A-1DN, and I am having problems connecting a camera to the USB ports, as well as the integrated webcam not being recognised.
I am using Ubuntu 16.04 with kernel 4.13.0-45-generic
After plugging in an external webcam, lsusb does not change, indicating no device has been recognised.
ls -ltrh /dev/video* returns the error: ls: cannot access '/dev/video*': No such file or directory
I have tried installing uvcvideo, but the most up to date version is already installed. Related to this, I cannot access the Video4Linux module required to use one of the two cameras I am trying to use.
I am aware of the same question being posted here: cannot access /dev/video*: No such file or directory but I can't seem to make that solution work for me.

Answer 1

In dev is there root direct:
my#my-u18gv:~$ cd /dev/video0
If the bellow msg come:
No such file or directory
Then there may be two cases if i found and try to fix:
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1.) The ubuntu machine or linux machine.
*
There may be various scenario or dependencies which may be causing
this but this what i check on both condition. The the packages and
retart the system
sudo apt-get update
To check the webcamp you can use cheese or any other it depends on
you:
sudo apt-get install cheese
cheese
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2.) Ubuntu in Virtual Machine running on windows.
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I'm using ubuntu 18.04, virtual machine 5.2.14 on windows 10 64bit.
Steps:
Open the VM Virtual Box and select the snapshot you are using.
Select the Settings
Select the USB menu at the left
Enable the usb controller and select the USB 2.0 (EHCI) cintroller
Click from USB Device_filter there is a usb cable icon with '+' sign at the right side.
Select your device from the list. In my list it was realtek semiconductor corp.
Here you may face one issue:
while selecting and USB 2.0 and when you start then if you get below error.
failed to install extension pack VERR_SYMBOL_NOT_FOUND ..
Then you need to install VM VirtualBox Extension Pack.
Note: take care that the version of the VM virtualbox and extension package should be same or it might give you error.
Steps: For installing VM VirtualBox Extension Pack
link:https://www.virtualbox.org/wiki/Download_Old_Builds_5_2
For every version you will find the extension package you need in above link.
Open the VM Virtual Box and click on File --> Preferences --> Extensions
Click on Plus icon and Add the extension which you downloaded.

Answer 2

Execute the command:
enter image description here
system error:
[ERROR] [1575905480.653251919]: Unable to identify '/dev/video0': 2, No such file or directory
enter image description here
Answers:
First of all, try your own laptop camera good or bad (do a QQ search, etc...); no problem found
Then review the virtual machine settings. The blue circle has not been opened before and the virtual machine must be turned off for it to be marked;
enter image description here
Reboot, the camera device can now be found in the virtual machine and check "Connect (disconnect from host)".
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Re-run the command, the camera can open correctly
enter image description here
I hope it works