How can I change the password on my craftsman keypad garage door opener when I forgot the current password it has on it. The model number is 139.53684 I have the keypad but I don't remember the password that was put in it. So I need to be able to wipe it out and start like if it was new, or reset the password. Because I don't remember the old password in order to change it.

Guessing, I would press the learn button on operator, till learn led changes states, then enter 4 digit code, press enter, on some if you press learn button too long, it will erase ALL Codes.
If this is the only transmitter, It would not hurt to clear any old or unknown Transmitters.