Refrigerator / Freezer not cooling

Neither the refrigerator or freezer are cooling properly. The compressor runs and the circulating fan is running. I have removed the back panel in the freezer and the coils are not iced up. At the highest setting the freezer will not even make slush in the ice trays and the refrigerator is barely cool. Just prior to this, for about two weeks, the refrigerator was freezing liquids, icebergs floating in the milk and tea pitcher, etc., and the freezer was fine. This occured regardless of the temperature setting.

HELP PLEASE !! I’d hate to have to buy a new one!