Rigidbody movement not working after build

After I build the game, none of the buttons to move or jump work.

• The movement works fine in the editor.

• the rigidbody still is affected by gravity after the build.

• the inputs for pausing still work after the build.

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I've tried restating my computer and moving the files to a new project, but it didn't work.

Here is my movement script \/\/\/

 using System;
 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityStandardAssets.CrossPlatformInput;
 using UnityStandardAssets.Utility;
 using UnityStandardAssets.Utility.Inspector;
 
 public class playerMovement : MonoBehaviour
 {
     public float WalkSpeed = 400;
     public float RunSpeed = 500;
     public bool IsGrounded;
     public bool CanMove = true;
     public GameObject Player;
     public GameObject ResumeButton;
     public Rigidbody PlayerRb;
     public float HorizontalAxis;
     public float VerticalAxis;
     public float JumpForce = 150;
     public float MovementSpeed = 400;
     public KeyCode Pause;
     public KeyCode Run;
     public Vector3 MoveDirection;
     public Vector3 YVelFix;
     void Awake()
     {
         Run = KeyCode.LeftShift;
         Pause = KeyCode.Escape;
         Player = GameObject.FindWithTag("Player");
         PlayerRb = Player.GetComponent<Rigidbody>();
     }
 
     private void Start()
     {
         CanMove = true;
         ResumeButton.SetActive(false); //immediatly turns off the pause menu
     }
 
     private void OnTriggerEnter(Collider other)//ground check
     {
         IsGrounded = true;
     }
     private void OnTriggerExit(Collider other)//ground check
     {
         IsGrounded = false;
     }
 
     void Update()
     {
         if (Input.GetKey(KeyCode.A))//left movement
         {
             HorizontalAxis = -1;
         }
         else if (Input.GetKey(KeyCode.D))//right movement
         {
             HorizontalAxis = 1;
         }
 
         if (Input.GetKey(KeyCode.S))//back movement
         {
             VerticalAxis = -1;
         }
         else if (Input.GetKey(KeyCode.W))//forward movement
         {
             VerticalAxis = 1;
         }
         if (Input.GetKeyUp(KeyCode.A))//stops movement
         {
             HorizontalAxis = -0;
         }
         if (Input.GetKeyUp(KeyCode.D))//stops movement
         {
             HorizontalAxis = 0;
         }
 
         if (Input.GetKeyUp(KeyCode.S))//stops movement
         {
             VerticalAxis = 0;
         }
         if (Input.GetKeyUp(KeyCode.W))//stops movement
         {
             VerticalAxis = 0;
         }
         MoveDirection = (HorizontalAxis * transform.right + VerticalAxis * transform.forward).normalized;//finds direction of movement
     }
     
     void FixedUpdate()
     {
         // Running
         if (Input.GetKey(Run))//run button
         {
             MovementSpeed = RunSpeed;
         }
         else
         {
             MovementSpeed = WalkSpeed;
         }
 
         // Pausing
         if (Input.GetKeyDown(Pause))//pause button
         {
             if (CanMove == true)
             {
                 Button.SetActive(true);
                 CanMove = false;
                 Time.timeScale = 0.2f;
             }
         }
 
         if (CanMove == true)//jumping
         {
             if (CanMove == true && IsGrounded == true)
             {
                 if (Input.GetKey(KeyCode.Space))
                 {
                     PlayerRb.AddForce(Vector3.up * JumpForce);
                 }
             }
             Move();
         }
     }
 
     public void Resume()//resume button for pause menu
     {
         CanMove = true;
         Time.timeScale = 1.0f;
         Button.SetActive(false);
     }
 
     void Move()//movement
     {
         YVelFix = new Vector3(0, PlayerRb.velocity.y, 0);
         PlayerRb.velocity = MoveDirection * MovementSpeed * Time.deltaTime;
         PlayerRb.velocity += YVelFix;
     }
 }