Anti-Gravity isn't working

Hello! I am new to using Unity and I'm hoping for a hint about where the problem may be in my code that is preventing my gravity to inverse from being applied every time I hit the button to "flip" my character (rotate the char upside down to walk on the ceiling or floor)

  if (Input.GetKeyDown(KeyCode.G))
         {
             if (isFlipped == false)
             {
                 if (player.isGrounded)
                 {
                     transform.position = transform.position + Vector3.up * 2;
                 }
                 Debug.Log("Attempting to Flip");
                 currentAngle = transform.eulerAngles;
 
                 //lock controls until flipping completes : not yet made (don't worry about it)
 
                 Vector3 rot = transform.rotation.eulerAngles;
                 rot = new Vector3(rot.x, rot.y, rot.z + 180);
                 transform.rotation = Quaternion.Euler(rot);

 
                 isFlipped = true;
             }
             else
             {
                 Debug.Log("Attempting to Flip");
 
 
                 //lock controls until flipping completes
 
                 Vector3 rot = transform.rotation.eulerAngles;
                 rot = new Vector3(rot.x, rot.y, rot.z - 180);
                 transform.rotation = Quaternion.Euler(rot);

 
                  isFlipped = false;
              }
 
          }
 
 
 //jumping
          if (isFlipped == false)
          {
              if (player.isGrounded)
              {
                  vSpeed = 0;
                  if (Input.GetKeyDown(KeyCode.Space))
                  {
                      vSpeed = jumpHeight;
                  }
              }
              //gravity
              vSpeed -= gravity * Time.deltaTime;
              movement.y = vSpeed;
 
          }
          else
          {
              gravity = gravity * -1;
 
              if (player.isGrounded)
              {
                  vSpeed = 0;
                  if (Input.GetKeyDown(KeyCode.Space))
                  {
                      vSpeed = jumpHeight * -1;
                  }
              }
              //gravity
              vSpeed += gravity * Time.deltaTime;
              movement.y = vSpeed;
          }
 
 
          movement = transform.rotation * movement;
          player.Move(movement * Time.deltaTime);