refrigerator not cooling
First off, understand how a refrigerator moves cold air around between the freezer compartment and the cold food compartments. Here is a generic diagram. 


So make sure you have not stored something in a way that is blocking the airflow. If not, then find and inspect those air pathways to see if there is ice, mold or some other material built up and blocking it. I have had a small piece of cellophane from something get caught in the vent and cause this.

If that's not it, roll the fridge out and vacuum the dust off of the evaporator coils. Diminished capacity will allow the cooling to handle the freezer, but not much else, so the temperature controls will often prioritize the freezer.