i can't move my player by clicking button - unity3d

Question

My player GameObject is AlienPlayer
i want to move player by click of the button
code works on keyboard controls but not on click of a button
This is my update():
void Update()
{
movement = Input.GetAxis ("Horizontal");
if (movement > 0f) {
left();
}
else if (movement < 0f) {
right();
}
else {
rigidBody.velocity = new Vector2 (0,rigidBody.velocity.y);
}
if (moveLeft) { left(); }
else if (moveRight) { right(); }
}
public void left()
{
rigidBody.velocity = new Vector2(movement*speed, rigidBody.velocity.y);
//rigidBody.AddForce(transform.forward * speed, ForceMode2D.Force);
transform.localScale = new Vector2(2f, 2f);
}
public void right()
{
rigidBody.velocity = new Vector2(movement * speed, rigidBody.velocity.y);
transform.localScale = new Vector2(-2f, 2f);
}
And this for event trigger:
public void LeftBtnDown()
{
moveLeft = true;
}
public void LeftBtnUp()
{
moveLeft = false;
}
public void RightBtnDown()
{
moveRight = true;
}
public void RightBtnUp()
{
moveRight = false;
}
**I want to make this control for android **

Answer 1

Your code seems to be logically functional, my first guess would be that you don't have an event system any where in your scene.
You can create one simply by clicking on the + in the hierarchy menu -> UI -> EventSystem.
I don't believe the code is the problem, but if the EventSystem does not turn out to be the issue, you could try changing your Update method to this:
void Update()
{
movement = Input.GetAxis ("Horizontal");
if (movement > 0f || moveLeft) {
left();
}
else if (movement < 0f || moveRight) {
right();
}
else {
rigidBody.velocity = new Vector2 (0,rigidBody.velocity.y);
}
}
If that does not work, I would need additional information to help you.