Freezer and Refrigerator not cold.

Remove the back cover inside the freezer, with a hair dryer, defrost the frosts built up over the fringes, only the 4 sides of the back panel needs to be defrost so that I can get access to the heater and Thermostat. The heater is a tube like and if it looks black, it is bad, the new one is filled with aluminum coils inside the tube that you can see. Replaced the heater and everything worked. It has been fine for a week now.