Check that the strand is plugged in securely
Test the outlet with another device
Inspect the fuse in the plug and replace it if blown
Make sure any dimmer or timer is set correctly
Look for a loose bulb in the dark section and tighten it
Replace any burned-out bulb with the correct type
Check for a missing bulb if the strand requires one to complete the circuit
Gently wiggle bulbs to find intermittent connections
Inspect the wire for cuts, breaks, or pinched sections
Separate tangled wires and straighten the strand
Test sections one by one if the lights have multiple strands connected
Replace the entire strand if the wiring is damaged or the problem persists