The refrigerator and freezer are not cooling the freezer reads 12 and the refrigerator is 42

I am a celcius man myself. So I assume you are talking about degrees fahrenheit?
Basically you are not getting the correct temperatures in the refrigerator or freezer. this could be due to
# Condenser fan not working (condenser is the outside of the fridge that gets hot)
# condenser blocked or dirty
# Poor air flow over the condenser
$ evaporator fan not working (this circulates cold air inside the fridge)
$ The ducting for the cold air is blocked
$ the themostat is faulty
& Compressor has burnt valves and cannot pump properly
* the fridge is loosing refrigerant