Unity 2D -- Dash instantly stops

Hello, I've been working on a simple 2D platformer for a school project! I'm currently making a dash ability for my game, but I've encountered an issue. Whenever I try to dash, it instantly ends barely making me move forward. Can somebody help me fix this issue? I've tried to apply many methods but I couldn't figure it out. Here's the script:

 [SerializeField] private float speed;
 [SerializeField] private float jumpPower;
 [SerializeField] private LayerMask groundLayer;
 [SerializeField] private LayerMask wallLayer;
 private Rigidbody2D body;
 private Animator anim;
 private BoxCollider2D boxCollider;
 private float wallJumpCooldown;
 private float horizontalInput;
 private float waitTime = 2.0f;
 private float timer = 0.0f;
 private float visualTime = 0.0f;
 private bool canDash;

 private void Awake()
 {
     body = GetComponent<Rigidbody2D>();
     anim = GetComponent<Animator>();
     boxCollider = GetComponent<BoxCollider2D>();
 }

 private void Update()
 {
     float horizontalInput = Input.GetAxis("Horizontal");

     if (horizontalInput > 0.01f)
         transform.localScale = Vector3.one;
     else if (horizontalInput < -0.01f)
         transform.localScale = new Vector3(-1, 1, 1);

     anim.SetBool("Running", horizontalInput != 0);
     anim.SetBool("grounded", isGrounded());
     anim.SetBool("onWall", onWall());

     if (wallJumpCooldown > 0.2f)
     {
         body.velocity = new Vector2(horizontalInput * speed, body.velocity.y);

         if (Input.GetKey(KeyCode.Space))
             Jump();
         if (Input.GetKey(KeyCode.C))
             Dash();
     }
     wallJumpCooldown = 3f;

     if (wallJumpCooldown < 0.2f)
     {
         speed = 0;
     }
 }

 private void Jump()
 {
     if (isGrounded())
     {
         body.velocity = new Vector2(body.velocity.x, jumpPower);
         anim.SetTrigger("Jump");
         canDash = true;
     }
     else if (onWall() && !isGrounded())
     {
         body.velocity = new Vector2(-Mathf.Sign(transform.localScale.x) * 16, 14);
         wallJumpCooldown = 0.1f;
     }
 }
 //Here is the Dash, need help here.
 private void Dash()
 {
     if (!isGrounded() && !onWall() && canDash)
     {
         body.velocity = new Vector2(Mathf.Sign(transform.localScale.x) * 20, 0);
         canDash = false;
     }
 }

 private bool isGrounded()
 {
     RaycastHit2D raycastHit = Physics2D.BoxCast(boxCollider.bounds.center, boxCollider.bounds.size, 0, Vector2.down, 0.1f, groundLayer);
     return raycastHit.collider != null;

 }

 private bool onWall()
 {
     RaycastHit2D raycastHit = Physics2D.BoxCast(boxCollider.bounds.center, boxCollider.bounds.size, 0, new Vector2(transform.localScale.x, 0), 0.1f, wallLayer);
     return raycastHit.collider != null;
 }