If your garage door is raised using an automatic opener, you may never have used the manual locking feature of your door. A centrally located lock in an overhead door is usually operated by a T-handle that is connected to a lock bar system. When the T-handle is turned, the lock bars insert into slots in the vertical tracks at each side of the door, locking it into place. A corroded or damage T-handle can be removed for repair or replacement.
Loosen and remove the retaining screws from the lock box on the inside surface of the garage door opposite of where the T-handle is mounted with a Phillips screwdriver.
Slide the lock box off the square shaft protruding through the garage door from the T-handle. Slide the lock box downward and away from the protruding end of the T-handle retaining screw.
Remove the T-handle retaining screws from the outside of the door with a Phillips screwdriver.
Slide the T-handle straight out from the garage door and remove it.