no power to fuse box or headlight switch?

check fusible links by the starter probably one of them are burnt up. they are available at auto parts. should have 12 volts on both sides.

I agree with HMAC300, there are fusible links down at the starter which get old and fail. Here are the locations of the links so you can check them out, just pull on them, if they stretch they are bad. Check out the images (below). Please let us know what happens.