Unplug the lights before handling them
Check the outlet with another device
Inspect the plug, cord, and bulbs for visible damage
Replace any blown fuse in the plug
Tighten any loose bulbs
Replace missing or broken bulbs with the correct type
Test the light string after each repair
Check for damaged wires or exposed copper
Cut out and replace damaged sections if the lights are repairable
Use a bulb tester or multimeter to find the fault
Replace the entire string if the wiring is badly damaged
Keep replacement bulbs and fuses matched to the light set
Store lights carefully after use to prevent future damage