There are several steps you can take to fix your LED Christmas tree lights: 1. Check the fuses: Make sure the fuse on your LED Christmas tree lights is not blown. If it is blown, replace it with a new fuse of the same size and type. 2. Check the connections: Make sure all the connections are secure and tight. If any of the connections are loose, tighten them up to make sure the circuit is complete. 3. Check the bulbs: Make sure the bulbs are not burned out. If a bulb is burned out, replace it with a new one of the same type and size.