My Character won't jump

I was following a 2D platformer tutorial on youtube and soon after changing a few settings for the game object, my character won't jump. I have no experience in C# so any help is greatly appreciated. Thank you in advance. Attached is the code I used from following the tutorial.

using UnityEngine; using System.Collections;

public class Movement : MonoBehaviour{

 public float moveSpeed;
 public float jumpHeight;
 private float moveVelocity;

 public Transform groundCheck;
 public float groundCheckRadius;
 public LayerMask whatIsGround;
 private bool grounded;

 private bool doubleJumped;


 private Rigidbody2D myRigidBody2D;

 //  Use this for initialization
 void Start(){
     myRigidBody2D = GetComponent <Rigidbody2D>();
 }

 void FixedUpdate(){

     grounded = Physics2D.OverlapCircle(groundCheck.position, groundCheckRadius,whatIsGround);
 }


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

     if (grounded)
     {
         doubleJumped = false;
     }
         

     if (Input.GetKeyDown(KeyCode.Space) && grounded )
     {
         //myRigidBody2D.velocity = new Vector2(myRigidBody2D.velocity.x,jumpHeight);
         Jump();
     }

     if (Input.GetKeyDown(KeyCode.Space) && !doubleJumped && grounded)
     {
         //myRigidBody2D.velocity = new Vector2(myRigidBody2D.velocity.x, jumpHeight);
         Jump();
         doubleJumped = true;
     }

     moveVelocity = 0f;

     if (Input.GetKey(KeyCode.D))
     {
         //myRigidBody2D.velocity = new Vector2(moveSpeed,myRigidBody2D.velocity.y);
         moveVelocity = moveSpeed;

     }

     if (Input.GetKey(KeyCode.A))
     {
         //myRigidBody2D.velocity = new Vector2(-moveSpeed,myRigidBody2D.velocity.y);
         moveVelocity = -moveSpeed;
     }

     myRigidBody2D.velocity = new Vector2(moveVelocity, myRigidBody2D.velocity.y);

 }

 public void Jump(){
     myRigidBody2D.velocity = new Vector2(myRigidBody2D.velocity.x, jumpHeight);
 }

}