Freezer worked, frig not cooling

First, read through blogs which said it could be something frozen up. I unplugged and let it warm for a few days. Didn't work. No ice found. Then, assumed to be thermostat. Unplug frig. One screw removes cover, then another 2 screws to take out thermostat compartment. Unplug wires from harness and remove. Simply put in the new thermo (reverse from removal), and reassemble. Bingo, nice and cool within 12 hr. Rock solid 35F ever since. Pretty simple.