[TedLaRue]

In the absence of other more knowledgable replies, I'll venture a guess.

Does anything else electrical work?

Suddenly not working electrically could result from rodents damaging the wiring.

Tractors (and cars) often have a "fusible link" in the wire from the battery to the rest of the system (not the heavy wire to the starter). This link behaves like a fuse but doesn't look like a fuse. To check for it, follow the wires from the battery to whereever they go. A fusible link would probably be a short section of wire with a connector on each end.

If it does turn out to be the fusible link, the next big question is "Why did it blow?".