how can i get my van started?

I have a 1994 ford conversion van(178k mi), recently it stopped starting,it wont do anything! its as though the battery was removed from the vehicle,nothing lights up, absolutely nothing,i checked the battery voltage and its good(right at 12v),there' no power to the vehicle at all. I know a little about the fusible links but dont know where they are located or where to start, can you help? Thanks.