To fix Christmas lights that don't work, make sure electricity is getting to the lights and check the light fuses. If no problems are found, check each individual light. The length of time it takes to complete this task depends on the problem you find with the Christmas lights.Continue Reading
Check the fuse box to make sure one of the circuits hasn't been tripped and there are no blown fuses. If either of these issues is found to be the problem, either reset the circuit breaker, or change the blown fuse.
Inspect the electrical sockets the lights are plugged into to make sure they are working. Turn off the power to the sockets, and remove the face to make sure it is still connected. If the wires are connected, restore power, and test with a circuit tester.
Look in the compartment near the plug of the lights to determine if there are any blown fuses. If any of the fuses are blown, replace them.
If nothing else rectifies the problem, check each individual light for a loose or blown bulb. If you find a loose or blown bulb, either tighten or replace the bulb entirely.