If the freezer is working fine but the refrig part is not cooling here's something you might try. Depends on the make/model of your unit.
Open the refrigerator door and look in the inside on the back wall. In back of the refrigerator section there are probably aluminum fins. On those fins may be a small clip with a wire connected somewhere. Make sure the clip is slid over one of the fins. Check that the wire from the clip is attached to its plug. Then slide the small clip down on the fin.
This will tell your unit it needs colder air to refrigerator part.