No one turned off your power switch up above the refrigerator, I trust. So, either your power supply or your main PCB is blown. Check the fuse on the main PCB (up on top of your refrigerator in the compressor area). The fuse will be right next to that round, black piezo electric speaker on the main PCB board as shown here:
If that's not it, then check to see if your power supply board is supplying power by measuring the voltage on JP11 of the Main PCB. You should see 26 vdc between pin 3 (GND) and pin 1. And, you should see 12 vdc between pin 3 (GND) and pin 2.
If you don't get those voltages, then you might have a bad Power Supply Board. It looks like this:
Also of note, your 120vac going into the Main PCB board comes in on JP8, pin 1 (WHT) and pin 5 (RED).
I don't know if you will be able to see the larger image of the schematic, or if Fixya will just give you a thumbnail, but I'll try to post it here, anyway:
Well, good luck and let me know if you need any more assistance.