It's really hard to say. But what you need is 12 volt to the light and a good ground. I would start measuring at the switch. Get a service manual and figure out where the wire to the headlights is located and measure for voltage there. Also, measure the voltage from the fuse box to the switch. If you've got voltage at the switch, but the lights don't go on, you need to look further down the circuit towards the light. Check for voltage at the lights. If you've got 12 volts there, you can start hunting for a bad ground. But you just might have a bad switch.
If you're in too much of a hurry to wait for a service manual, let me know and I'll check the color of the switch wires you need to measure.
