Two possibilities- - - -both high beams burned out, or a bad dimmer switch. Try applying voltage directly to the headlight connections with a jumper wire at the back of the headlights. Two wires will be high and low beam, the other one is the ground. DON'T attach the hot wire to the ground, you'll get a big arc! I'm betting on a bad dimmer switch, they had a habit of failing pretty often.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!