Answer!!!
You may have a bad/loose ground wire somewhere (probably in the front end), and/or a short in the wiring harness where only one headlight comes on. My guess is the impact shock knocked something loose.
You could confirm this by unplugging all the lights at front, then pull the light switch all the way out. Do the dash lights and tail lights stay on as they should? If so, plug in one light in front at a time in front, and look at the dash and tail lights. You might be able to isolate the offending bulb or circuit in this manner. Check the ground circuit for the lights at the front.