Gather all of the remotes that you wish to reset. Keep them close for easy access.
Position a step ladder underneath the main motor unit of your Craftsman garage door opener. Ascend the ladder so that you can reach the unit.
Locate the "Learn" button the main motor unit. Press and hold the "Learn" button for six seconds or until the indicator LED turns off. This will deactivate all of your remotes.
Resync your remote by pressing the "Learn" button on the motor unit. Within 30 seconds of pressing "Learn" on the main unit, press the button on the remote you wish to reprogram.
Continue holding the button on the remote until the LED on the main unit begins to blink. When the LED blinks, the remote and door opener have been reconnected.
Repeat steps two and three until all remotes have been reconnected.