Only my headlights come on

The switch has a small stem release button on one side, either bottom or right. They are oriented differently in different vehicles so I'm guessing. Feel around for it. Disconnect battery, pull stem to full on. Push that small button so stem pulls the rest of the way out. Work bezel nut off, switch falls out. Remove its harness connector. Or you could put the stem back in, reattach battery and further diagnose. anyway...
Don't push the little button when reinstalling the stem. The stems tapered point should guide it past the latch.