Does it try to crank at all or just dead?? If it is just dead I would try the fuses 1st. then checking the battery. If it make a noise like it tries to start but can't just can't even turn over if the battery is good it may have oil in the cylinders. A friends cbr600rr was thrown in a creek took forever to get it cranked a battery charger and turning the back wheel while in gear finally got it cranked (smoked like crazy). That would probably only be if it fell over though.
With the headlight not coming on I would say a fuse thought, most of the newer bikes won't crank unless the headlight comes on these days, you could also trace the ignition wire jump the wires with a paper clip and see if i will crank I would look into the fuses first