How to double jump? i just can jump once when it touch the ground.. help me guys =D

private bool jumping; private bool sliding; private bool wallHolding; private bool stopSliding;

 // Components
 private PlayerPhysics playerPhysics;
 private Animator animator;

// private GameManager manager;

 void Start () {
     playerPhysics = GetComponent<PlayerPhysics>();
     animator = GetComponent<Animator>();
     //manager = Camera.main.GetComponent<GameManager>();
     animator.SetLayerWeight(1,1);
 }
 
 void Update () {



     // Reset acceleration upon collision
     if (playerPhysics.movementStopped) {
         targetSpeed = 0;
         currentSpeed = 0;


     }

     //player slash

     if (Input.GetButtonDown("slashing"))
     {
         animator.SetTrigger("slash2");
     }

     // If player is touching the ground
     if (playerPhysics.grounded) {
         amountToMove.y = 0;
         
         if (wallHolding) {
             wallHolding = false;
             animator.SetBool("Wall Hold", false);
         }
         
         // Jump logic
         if (jumping) {
             jumping = false;
             animator.SetBool("Jumping",false);
         }
         
         // Slide logic
         if (sliding) {
             if (Mathf.Abs(currentSpeed) < .25f || stopSliding) {
                 stopSliding = false;
                 sliding = false;
                 animator.SetBool("Sliding",false);
                 playerPhysics.ResetCollider();
             }
         }
         
         // Slide Input
         if (Input.GetButtonDown("seret")) {
             if (Mathf.Abs(currentSpeed) > initiateSlideThreshold) {
                 sliding = true;
                 animator.SetBool("Sliding",true);
                 targetSpeed = 0;
                 
                 playerPhysics.SetCollider(new Vector3(10.3f,1.5f,3), new Vector3(.35f,.75f,0));
             }
         }
     }
     else {
         if (!wallHolding) {
             if (playerPhysics.canWallHold) {
                 wallHolding = true;
                 animator.SetBool("Wall Hold", true);
             }
         }
     }
     
     // Jump Input
     if (Input.GetButtonDown("Jump")) {



         if (sliding) {
             stopSliding = true;
         }
         else if (playerPhysics.grounded || wallHolding) {
             amountToMove.y = jumpHeight;
             jumping = true;
             animator.SetBool("Jumping",true);
             
             if (wallHolding) {
                 wallHolding = false;
                 animator.SetBool("Wall Hold", false);
             }
         }
     }