Radio doesn't work

First thing to check here is the fuses - make sure they aren't blown and test the ones related to the radio and even cigarette lighter 12V with a multimeter. If the fuses check out, you will want to verify the voltages on the wiring using this pinout, but using the same multimeter to do so. If both the wiring and fuses are good, it is likely an issue with the radio.
As a last resort, get the car scanned with a proper all system scanner like an Autel - you can usually get this done for free at a place like AutoZone or Advance Auto. I own the scanner to do it, but for occasional use, shelling out over $300 for independence is a lot.

If you find it could be a radio issue, you can always try to open it up and look for an obvious failure inside - sometimes it's as simple as a bad solder joint, for example. Other times, diagnosing it can be complex, and the time you spend fixing it may not make sense. If it comes down to that, depending on your current radio, you can probably get a used radio online or from a junkyard. If it has a navigation system, you'll likely need to update the maps, especially a used one, which will likely have an old maps package installed. Toyota is one of those manufacturers it's a crapshoot - sometimes it has to be done on a dealer computer with the newer cars, others can be done with update DVDs or a update USB drive, others are updated by replacing a component like the SD card (which in that case if it's just an SD card you may be able to move the one from the dead radio over to the new one as long as it doesn't S/N lock).