Could be one of the carb floats is stuck or the rollover caused it to come off its mounting position. As fuel enters the carb, the float rises with the fuel level until it reaches a position that shuts off any more fuel entering the float chamber and prevents an overflow. Fuel level drops, float drops and fuel flows again. Basically like the cistern in a toilet.
Here's a link that should help you.
Lousy bulbs or poor voltage regulation (too high voltage will burn out incandescent lamps especially when you factor in all the bumps and vibrations ). Maybe you can special bulbs designed to withstand the conditions presented by your ATV.
Needs a new needle & seat in the carb.
These machines depend on a good ground. Make sure your ground connections are all clean and tight.... especially the ground wire from the battery to the frame. I recommend removing the battery terminal wires and cleaning the terminals... Also the negative cable that bolts to the frame... remove the bolt and sand the terminal that bolts to the frame. Check for in-line fuses... There is one in-line fuse near the battery!