OK, this a really a SWAG but check (books and such, or call the dealer) and see if there is a fuse inline between the battery and the starter. (REALLY! Not the fuse box, inline on the battery cable!)
Up until a few months ago I had NEVER heard of this, but my sister-in-law's '94 Grand Marquis had the same problem. Everything seemed fine, but absolutely NOTHING when you turned the key. Had to pay to have it diagnosed and that's what it turned out to be.
NOT one of Ford's better ideas........
Actually, you could look yourself. I never saw a reason to actually go and see where it is.... Crawling under a Grand Marquis is a little frightning