how do you fix a christmas tree lights

*Santa Claus thinks for a moment* "Well, the first thing you should do is check the bulb. If it's burnt out, you need to replace it. If it's not burnt out, try changing the fuse in the plug. If that doesn't work, try checking the connections. Make sure all the wires are securely attached to the plugs. If that still doesn't work, try changing the socket on the wall or replacing the whole string of lights. Let me know if that helps."