Double Jump NoT Working

So i was working on my double jump system but it cant double jump i am a complete beginner and i dont know what causes this please help

My Code: using System.Collections; using System.Collections.Generic; using UnityEngine;

public class PlayerMovement : MonoBehaviour { public ParticleSystem dust; public float runSpeed = 35f; float horizontalMove = 0f; public CharacterController2D controller2D; public Animator animator; private int extraJumps; public int jumpValue; bool jump = false; bool crouch = false; private bool grounded; public Transform groundCheck; public float checkRadius; public LayerMask whatIsGround;

 void Start()
 {
     extraJumps = jumpValue;
 }

 void Update()
 {
     horizontalMove = Input.GetAxisRaw("Horizontal") * runSpeed;

     animator.SetFloat("Speed", Mathf.Abs(horizontalMove));

     if (grounded == true)
     {
         extraJumps = jumpValue;
     }
     

     if (Input.GetButtonDown("Jump") && extraJumps > 0)
     {
         jump = true;
         animator.SetBool("isJumping", true);
         extraJumps--;
     }else if (Input.GetButtonDown("Jump") && extraJumps == 0 && grounded == true)
     {
         jump = true;
         animator.SetBool("isJumping", true);
     }

     if (Input.GetButtonDown("Crouch"))
     {
         crouch = true;
     }else if (Input.GetButtonUp("Crouch"))
     {
         crouch = false;
     }
     if (horizontalMove == 35f)
     {
         CreateDust();
     }else if (horizontalMove == -35f)
     {
         CreateDust();
     }
     
      
     
 }

 public void OnLanding()
 {
     animator.SetBool("isJumping", false);
 }
 public void OnCrouching(bool isCrouching)
 {
     animator.SetBool("isCrouching", isCrouching);
 }

 void FixedUpdate()
 {
     grounded = Physics2D.OverlapCircle(groundCheck.position, checkRadius, whatIsGround);
     controller2D.Move(horizontalMove * Time.fixedDeltaTime, crouch, jump);
     if (grounded == true)
     {
         jump = false;
     }
 }
 
 void CreateDust()
 {
     dust.Play();
 }
 void StopDust()
 {
     dust.Stop();
 }

}