If the headlights worked before you took it apart, the plug not pushed on the headlight switch properly, a spade terminal bent over, or the wiring plug with a melted terminal are possible causes. Check the dimmer switch for power as that's easier that pulling the switch panel back out, as power goes to the dimmer before it goes to the headlights. Good luck Ken
I had the same issue on my `Cuda. Every light on the thing worked except for the headlights. I traced it to a bad/dirty connection at the dimmer switch. Cleaned up the connector and the pins on the dimmer switch and I had working headlights once again!