If statement not activating commands

     void Update()
     {
         if (collideWithGround == true)
         {
             player.transform.Translate(Vector3.back * speedTwo * Time.deltaTime, Space.Self);
         }
         if (collideWithGround == false)
         {
             transform.Translate(Vector3.back * Time.deltaTime * speed);
         }
         if (Input.GetKeyUp(KeyCode.Mouse0))
         {
             collideWithGround = false;
             player.GetComponent<Rigidbody>().useGravity = true;
         }
     }
 
     private void OnCollisionEnter(Collision collision)
     {
         if (collision.gameObject.CompareTag("Ground"))
         {
             collideWithGround = true;
             player.GetComponent<Rigidbody>().useGravity = false;
         }
     }
 }

After it collides with the ground and activates the boolean, no matter what type of if command or coroutine or anything I use, I can't get it to deactivate the boolean. I've also tried replacing the if command in the collision method with a while, but that just breaks the entire unity program. Same goes for the useGravity = true command. It's almost as if the entire GetKeyUp if command just doesn't exist.