I have two "lift master" garage door openers
But, I would imagine they are all the same
If you havn't done so already, make sure and push and hold the two outside buttons until the red light flashes, this will reset it
I had my truck parked outside just in front of the garage doors. I went into garage, and pushed the little button on the back of the opener itself. A red light flashes on mine. Then I walked back to my truck and pushed and held the first button. Wait for the red light on the mirror to flash rapidly and then it should be programmed. Did the same with the other door and ditto
I hope that helps.