Ah, a broken light. That can be a real bummer on Christmas. Let's see...... to find the broken light, you'll need to start by looking at the plug and following the cord up the tree. Once you reach the top, carefully inspect each bulb and see if you can spot one that's not glowing. If you don't see a burned-out bulb, then it might be a faulty connection or a loose wire. In that case, you'll need to check each bulb's connection to the cord and make sure it's secure.