On my TC29DA there is a small fuse box, under the hood, on the front, right side of the firewall. There is a 10 amp fuse in it that is for the starting circuit. Check it.
If the starter does nothing when you turn the key, it must be the safety/relay/ neutral circuit. If it's not the fuse, start bypassing all the safeties till you find the problem. Of course, this is after you have made sure you are in neutral, sitting on the seat, PTO, etc. If it's none of these normal safety things you can switch the relays around to see if one of those is bad. First find the relays and switch the starter one with a similar one next to it. They just unplug. You can also jump the starter directly by connecting the wires on the starter to each other. Touch the solenoid (small) wire to the battery cable terminal (big wire) on the starter motor. Do this with a pair of pliers or a screwdriver or a wire and just touch the two. if it cranks the starter is good. Then you can work backward to the real problem.
Sometimes it can be frustrating to get to the real problem.