Head lights wont come on 2000 chev s 10 with switch

Sounds like a problem with the key switch.

It could be a fuse or a bulb. Do the 4 way flasher/hazard lights work?

If not, it could also be caused by a faulty multifunction switch. On some early 2000s models there was a recall.

https://recalls.gm.com/#/
GM RECALL CENTER

Check the vacuum switch under the hood in the center of the firewall...follow vac diag

Could be the starter solenoid.
The key switch sends power to the solenoid thru the neutral safety switch. You would need to check for power on the purple wire at the solenoid when the key switch is in the start position.

To disable the drl/auto lights press the dome override button 3 times.a chime will sound once you've successfully done it to let you know.

in the back of the head lights, the base is removed by grasping it and turning to the left and gently pulling outward,...the bulbs are pushed into the base,,,remove the bulb , hold it up to light to check the filaments....sometimes the back of the hdlite isn't easy to access, but otherwise it is an easy job....thnks for the question....hope info is helpful

sounds like you have a bad ground somewhere. Check every ground strap that you can find, make sure it's tight, and not corroded, etc. Sounds like the accessories are trying to find a ground, and going through the brake light to do so, thus burning out from too much current.

I would check the door adjar switches. IF all the door adjar switches check okay, then check the head light switch .

Assuming the head light switch and door adjar switches are okay , Then there is a wiring problem. This is the worst case scenario .

sounds like a o2 sensor run code scanner to see which on is bad

May want to check and see if the headlight sensor may be defective or covered, this could make the lights stay on, and the headlight would work the same as if it were dark outside.