How do you change the code on a garage door keypad without knowing the original code?

To change the code on a garage door keypad without knowing the original code, you typically need to reset the garage door opener itself. This usually involves locating the reset button on the motor unit, pressing and holding it until the lights blink or you hear a click, indicating the reset has been successful. After resetting, you can then program a new code according to the manufacturer's instructions. Be sure to consult the specific manual for your garage door opener, as procedures can vary by brand and model.