I typed the script and did everything, only that whenever I try to “play” to test it, the ball doesn’t move. Instead, when I look at the console, it says the error message when I try to move the ball with my arrow keys:

Also, in the inspector, it says, “The associated script cannot be loaded. Please fix any compile errors and assign a valid script.”
My script looks like this:
Please help!!!
Make it this way :
Create a Gameobject
Add Rigidbody to it
Add a collider to it
Now on PlayerController Script
public Rigidbody rb;
//Drag the gameobject to this parameter.
void Start ()
{
}
void FixedUpdate ()
{
rb.AddForce(your required force);
}
@dldbdms0630 Hi by any chance do you have the script slot of the component of your Game Object ("Player) empty? If so, click the circle next to the right of the text field (Missing (Mono Script)) and below the gear icon and select the GameController script.