Help! Bounce Machanic not working how how I want it to

I want to bounce a ball, but when the ball hits the ceiling the drag of the ball decreases or just changes to zero, the the ball waits A few seconds to turn the drag back on to simulate a bounce, but he code I wrote just laeves the drag at 1 when it his the ceiling and lands on the platform. Please Help!

using UnityEngine; using System.Collections; using UnityEngine.UI;

public class PlayerJump : MonoBehaviour {

 public AudioClip jumpClip;

 public Rigidbody2D rigidBody;

 public int movementSpeed, waitTime;

 bool hasHitCeiling;
  
 void Update () {
 }

 public void MoveRight(){
     transform.position += Vector3.right * Time.deltaTime * movementSpeed;
 }

 public void MoveLeft(){
     transform.position += Vector3.left * Time.deltaTime * movementSpeed;      
 }

 void OnCollisionEnter2D(Collision2D other){
     if(other.gameObject.tag =="Ceiling"){
         rigidBody.drag = 1;
         hasHitCeiling = true;
         if(other.gameObject.tag =="Hands"){
             StartCoroutine(ChangeBounce());
         }
     }
 }

  IEnumerator ChangeBounce(){
      yield return new WaitForSeconds(waitTime);
      rigidBody.drag = 0f;
      hasHitCeiling = false; 
  }

}