I just don't understand why it does not work?

Questions & Answers
1

using UnityEngine;

public class player1 : MonoBehaviour{

private player1 player;

public  Rigidbody rb;

public float ForwardForce = 100f;
public float SidewaysForce = 100f;

// Update is called once per frame
void FixedUpdate()

{ if (Input.GetKey(“w”) ) ;
{
rb.AddForce(0, 0, ForwardForce * Time.deltaTime);}

     if (Input.GetKey("a") ) ; 
     {
    rb.AddForce(SidewaysForce * Time.deltaTime, 0, 0);}

     if (Input.GetKey("d") ) ; 
     {
    rb.AddForce(-SidewaysForce * Time.deltaTime, 0, 0);}
 
     if (Input.GetKey("s") ) ; 
     {
    rb.AddForce(0, 0, -ForwardForce * Time.deltaTime);}

}
}

2

There are unnecessary semicolons after each if statement:

if (Input.GetKey("s") ) ;   // unnecessary semicolon

This will work:

using UnityEngine;

public class player1 : MonoBehaviour
{
	private player1 player;
	public  Rigidbody rb;
	public float ForwardForce = 100f;
	public float SidewaysForce = 100f;
	// Update is called once per frame
	void FixedUpdate()
	{ 
		if (Input.GetKey("w") )
		{ 
			rb.AddForce(0, 0, ForwardForce * Time.deltaTime);
		}

		if (Input.GetKey("a") )
		{
			rb.AddForce(SidewaysForce * Time.deltaTime, 0, 0);
		}

		if (Input.GetKey("d") )
		{
			rb.AddForce(-SidewaysForce * Time.deltaTime, 0, 0);
		}

		if (Input.GetKey("s") )
		{
			rb.AddForce(0, 0, -ForwardForce * Time.deltaTime);
		} 
	} 
}