Roll a Ball tutorial: Ball doesn't move

I don't know what's wrong, for everything seems correct. However, my ball just doesn't move no matter what :( I even tried to move it only forward using transformation.forward and still it didn't move. I would appreciate if anyone help me.

 using UnityEngine;
 using System.Collections;
 
 public class PlayerController : MonoBehaviour {
     
     public float speed;
     private Rigidbody rb;
     void Start()
     {
         rb = GetComponent<Rigidbody>();
     
     }
 
     void  FixedUpdate()
     {
         float moveHorizontal = Input.GetAxis("Horizontal");
         float moveVertical = Input.GetAxis("Vertical");
         Vector3 movement = new Vector3(moveHorizontal, 0.0f, moveVertical);
         rb.AddForce(movement * speed);
     }
 
 
 }