Sounds like a main power supply (check the big fuseable links in engine bay fusebox) has gone for some reason, to kill off all this stuff it needs to be a primary feed early in the system. Do things that should work even with the ignition off still work? You say the interior light came on, almost like you had turned off the ignition and the cab light illuminates? Could just be the ignition switch fried - but where does your tracker take power from (don't answer that on the forum) I assume a permanent supply so that casts doubt over it being the switch as the tracker should be on another supply - unless when the ign. switch died it took a fuseable link.
So, I would check fuses first, and try and work out just what does have power, if your tracker lost power then you will know where it gets it's feed so that will also help you to diagnose this. Check the back of the alt for solid connections, wires can corrode at terminals and can eventually simply snap.
If this isn't helping, or there is no obvious big wire/fuse off/broken/melted then you need to look deeper. I doubt it will be anything complicated, it really is a simple system.
Do you own a multimeter? If not, go and find a cheapy £10.00 one for this job. Set it to a range that includes 12V DC that's the solid line and the dashed line not the tilde, wavey symbol (AC). With the black probe on a good earth point (metal of the engine, alternator body, earth point etc.) you can then start to probe with the meter to check the back of the alt has 12v, then go to the main engine bay fusebox, every fuse on both sides should be live (with fuse fitted) then go from there.
