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.
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.
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.
Insert the retaining pin into the handle and gently tap the pin with the hammer until the pin is flush with the handle.