have to look at it to see what would need to be replaced. Take a few good pics of all the damage and I might be able to tell you more.
As for parts, wreckers or dealer I'd say for that(providing it is all stock)
you could put a test light across the terminals(with the headlights on) and see if you have voltage there. if so, clean up the terminals and you should be ok. If not, check to see if you have power to the hot side, by grounding your test light at a known good ground, then touching the probe side to the hot terminal. If good, you have a ground issue, of no light, its a power problem and you have to trace it back till you get power.
You can test the ground the same way, put the ground part of the test light on the ground wire of the headlight terminal, then put the probe onto a good power source. Illumination = good ground.