My keyless entry was working prior to vacation. We have two garage doors and each one has a different code. Only one code, and thus door, is now opening with the keyless entry pad. I replaced the battery, and that did not help. Any help is much appreciated. My garage door opener model number is 139.53675

See if this helps:
Liftmaster 972LM garage door opener remote

First check the power source for the operator that's not working, if it's got power, start tracing back to the keypad and make sure the wire didn't get chewed by something.

I believe these are wireless?

Door opener that is not working has lost its code. See attached instructions and reprogram.