What to do if a light isn't working?

If a light is not working, you should troubleshoot systematically from the simplest and safest checks to more involved electrical checks. First, check the bulb. Turn off power and try a new bulb that you know works in another fixture, because bulbs are the most common failure point, especially in garage door openers where vibration shortens filament life. Second, check power. Make sure the light switch is on, the circuit breaker is not tripped, and any GFCI outlets upstream are not tripped, as a tripped GFCI in a garage or bathroom can cut power to lights downstream. Third, check the switch. A light switch can fail internally. Try toggling it firmly and listen for a click. If you have a wall control for a garage door opener, press the light button to ensure it is not manually turned off. Fourth, inspect the socket. With power off, look for corrosion, blackening, or a bent tab at the bottom of the socket that is not making contact with the bulb. Gently pry the tab up slightly if needed. Fifth, for garage door opener lights, unplug the opener for 60 seconds to reset the logic board, and check the wiring connections at the motor head. If the opener moves but the light never comes on even with a new bulb, the logic board's light relay may have failed and the board may need replacement. If you are not comfortable working with electricity, call an electrician or garage door technician.