1998 Buick Park Avenue Light Problem

I had no problems with my car until tonight. Turned it off for a few minutes. Started car and all dash lights started flashing and headlights wouldn't come on. flipped the dimmer switch and flash stopped. All dashlights work now with no flashing, since I flipped the dimmer switch, but headlights won't come on, only parking lights. Parking lights and tail lights stay on. Had to disconnect the battery cable to make parking lights go off. Could it be the dimmer or a sensor controlling the delay lights? Headlights will not come on, although interior lights and parking lights will. Thanks for your help.