Jumping Stopped Working.

Hello, I edited the CharacterController.Move script, and now it won't jump, I don't know what I need to do to get it to work. Here's my current Script:

 var speed : float = 12.0;
 var jumpSpeed : float = 8.0;
 var gravity : float = 20.0;
 var RotateSpeed : float = 3.0;
 var SprintSpeed = 20;
 var Sprinting : boolean = false;
 private var moveDirection : Vector3 = Vector3.zero;
 
 function Update() {
 var controller : CharacterController = GetComponent(CharacterController);
 if (controller.isGrounded) {
 
 if (Input.GetButton ("Jump")) {
 moveDirection.y = jumpSpeed;
 }
 
 moveDirection = Vector3(0, 0,Input.GetAxis("Vertical"));
 //Rotate
 transform.Rotate(0,Input.GetAxis("Horizontal") * RotateSpeed, 0);
 moveDirection = transform.TransformDirection(moveDirection);
 moveDirection *= speed;
 
 if(Input.GetKey("up")){
 if(Input.GetKey(KeyCode.LeftShift)){
 transform.Translate(Vector3.forward * SprintSpeed * Time.smoothDeltaTime);
 Sprinting = true;
 }
 }
 }
 // Apply gravity
 moveDirection.y -= gravity * Time.smoothDeltaTime;
 
 // Move the controller
 controller.Move(moveDirection * Time.smoothDeltaTime);
 
 if(Sprinting){
 SprintingFunc();
 }
 
 }
 
 function SprintingFunc(){
 BreathDeduct();
 }
 
 function BreathDeduct(){
 //Take away some breath
 }

Thanks in advance for any help! :)