Unplug the lights before checking them
Inspect the entire strand for broken bulbs, loose bulbs, or damaged wires
Replace any burnt-out or missing bulbs with the correct type and voltage
Check that all bulbs are seated firmly in their sockets
Replace blown fuses in the plug if the strand has a fuse compartment
Test the outlet with another device to confirm it works
Reset any tripped GFCI outlet or circuit breaker
Separate and untangle the light strand to find hidden damage
Replace the strand if the wire insulation is cracked, frayed, or melted
Clean corrosion from bulb sockets and plug contacts
Test sections of the strand to isolate the bad part
Tighten loose connections between light strings
Use only compatible replacement bulbs for LED or incandescent lights
Store lights carefully after use to prevent future damage