Did you check the freezer section.
If the defrost system does not work, the evaporator will clog up with frost and not allow the air to flow through the cooling coils.
The freezer will stay frozen but will not have sufficient cooling
capacity for the refrigerator section (air flow is restricted, the fan in the freezer is supposed to draw air from the bottom of the freezer, through the evaporator coils, and out through the baffle at the top. The frost clog on the evaporator coils limits the air flow around themselves and decreases the amount of cold air to be directed into the refrigerator compartment)
The culprit could be a broken defrost heater element or the bimetal defrost element.
C.W., November 2007