Garage doors that do not operate with a garage door opener use keyed cylinder locks to secure the door. These types of locks usually mount in the center of the door and have two bars on the inside of the door that engage into the door tracks when you lock the door. Over time these locks will fail and need replacing. You can replace the door lock yourself within an hour. Most home improvement centers carry replacement garage door locks, or you can call a garage door dealer.
Close the garage door and secure the door down with a pair of vice grips. Place the vice grips on the door track above any door roller and lock the vice grips on the track. Remove the pin that secures the inside lock handle to the lock shaft in the center of the door panel. Place a nail over the pin and tap the nail with a hammer until you expose part of the pin. Grab the pin with a pair of pliers to remove the pin from the shaft.
Pull the inside handle off the shaft and pull the lock bars off the shaft. The lock bars are the two straight pieces going from the lock to each side of the door. The bars join on a plate that mounts over the lock shaft.
Disconnect the deadbolt lock above the shaft by removing the four securing screws with a Phillips-head screwdriver.
Remove the two screws that secure the outside lock assembly to the door with a Phillips-head screwdriver. Go outside and pull the lock assembly out of the door.
Take the outside lock assembly to a home improvement center. Find a matching lock kit that has the same distance between the two mounting holes as the existing lock. Most garage door locks will mount through two holes on the door section.
Ask a friend to slide the new outer door lock assembly through the door and hold the lock assembly. Secure the lock from inside the garage with two retaining screws.
Place the new deadbolt lock on the door. There is a thin bar from the outer door handle that extends through the door. Position the bar inside the back of the deadbolt and then attach the deadbolt to the door with the four retaining screws.
Position the lock bar through the lock bar guides on each side of the door. The guides are the two brackets that the lock bars sit in when the door is unlocked. Place the lock bar plate over the lock shaft.
Place the new inner lock handle on the shaft, lining up the hole for the retaining pin on the shaft and handle.
Insert the retaining pin into the handle and gently tap the pin with the hammer until the pin is flush with the handle.