Christmas is a time for decorations and lights. If you find that you have a dead strand of lights and you've tried everything to get them to work, the fuses of the lights might be your problem. Instead of throwing the old Christmas lights away, change the fuse and you get your lights working again.
Find the extra parts that came with your Christmas lights; there should be a few spare fuses.
Make sure the lights are unplugged.
Locate the part of the lights that plugs into the wall, and remove the cover to the fuse "box" of the Christmas lights. It may pop off or slide down.
Remove the old fuses.
Insert the new fuses into the box.
Replace the cover.
Plug the Christmas lights in.