Agree if there is NO power to anything its likely a connection issue, either at the battery, or the main ground on the block. Before towing it, go out with some booster cables, use only the negative jumper cable, put one end of the negative cable on the negative battery post, and the other end of the cable on the engine block, alternator case, etc.....a GOOD ground on the block. I'd do this with the lights on, then if they come on you'll know you're in the right area.
All you're doing here is making your own ground from the battery to the engine, so one cable should suffice. If this solves the problem, follow the negative cable from the battery and see where it connects to the block, IIRC its on the drivers side at the front.