Many garages will have a service door on either the side or the back. This door is generally able to be locked so that the items in the garage are safe and secure. If something happens to damage this lock, it will need to be replaced or people will be able to enter your garage whenever they please. Replacing an exterior lock is not any different than replacing an interior lock. The difference is the knob itself, as it is more sturdy because it has a key lock instead of a push button or turn knob lock
Use a screwdriver to remove the two screws securing the doorknob to the door. These screws should be located on the inside side of the door. Pull the two knobs apart and away from the door.
Insert the knob with the key hole, through the hole in the door. Make sure that the stem on the knob fits through the hole on the inner portion of the bolt.