if it does not work you need a new one
there are 2 types of system
older systems have 2 refrigerant coils . one in the fridge and another in the freezer. in this system the refigerant goes to freezer first and then goes onto the fridge. if the system is loosing refrigerant or the compresor is failing the fridge is the first thing to fail as there is not enough liquid refrigerant left to cool the fridge
newer systems duct the cold air from the freezer and control this with a motorised flap . if the flap fails or ice blocks the ducts then the fridge stops working
not sure which your system is but am thinking it may be the older one. in which case i would start looking to replace
Dave