96 Buick Park Ave no headlights
 

Suddenly, my headlights went out. Only the two headlights do not come on everything else works, and I checked the fuses and the circuit breakers in under the hood panel, took them all out for testing. Replaced them. Still no headlights, even with the manual switch. Called the garage and made an appointment. But, in the morning, the headlights were on! Cancelled the appointment. Now the headlights don't work again. Everything else is working. Nothing worse than an intermittent malfunction. Any ideas? We were taking a road trip the weekend, looks like I'll now have to rent a car.