I have a Frigidaire Gallery refrigerator which stopped freezing but stays cold enough to keep milk and beverages cool, also the refrigerator side stays cool also. I cleaned the dust from the air vent at the bottom on the back of the unit, unplugged overnight, plugged back in this morning, still won't freeze.

Check under your unit. Either the coils are blocked with dirt or the condenser fan is out or both. Fix it quickly or you will burn up the compressor. Remove front and rear covers after unplugging unit and vacuum and wash out coils with spray soap and a sprayer on a water hose. Clean fan blades. Slide out drain pan and clean, too. If it still will not cool you may have defrost system problems, but I doubt it from your description.