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.
Install the T-handle or its replacement in the reverse order of removal. Ensure the loop of the small helper spring on the lock bars is placed over the end of the bottom lock box retaining screw before it is tightened. Replacement T-handles for your garage door are available at hardware stores or where garage doors are sold.