It would help to post the make and model of your fridge.
However, without that my
advice is to first leave the door open and let it warm up inside for a day or two, meticulously clean the fridge in and out especially the
compressor,
heat exchanger, evaporator/plates, and any air passages associated with them. If you have a fan associated with your fridge make sure you also clean off the blades of the fan and that the fan
motor works.
Once you do all that, turn it on and see if it magically starts working again. If it doesn't, you can start
posting the particulars on your system and move forward from there.