Unplug the lights before handling them
Check the outlet with another device
Inspect the plug, cord, and bulbs for visible damage
Replace any blown fuses in the plug
Tighten any loose bulbs
Replace missing or broken bulbs with the correct type
Test each section separately if the strand has multiple sections
Check for a tripped breaker or blown house fuse
Reset any built-in circuit breaker on the light strand
Make sure bulbs are seated properly in their sockets
Clean corrosion or dirt from bulb contacts
Replace the entire strand if the wiring is frayed or damaged
Use a bulb tester to find the faulty bulb
Keep spare bulbs and fuses on hand for future repairs