freezer not freezing fridge not cooling

My freezer is as cool as the fridge not freezing or keeping ice cream frozen and my fridge does not keep items cold. what could cause this?

The fridge gets its cold air from the freezer through a vent between the freezer and fridge.The fan in the freezer blows air through it. There is a flap you adjust with the fridge temp. control. Make sure it’s opening and closing when you adjust the fridge temp …
If the evaporator coils behind the back panel of the freezer are icing up because of auto defrost failure that will stop the circulation of cold air and eventually affect the freezer too.

check defrost timer, defrost heater, defrost thermostat.http://www.acmehowto.com/howto/appliance/refrigerator/refrigerator.php

Part 6 is your timer>http://www.appliancepartspros.com/sect/5/s/9/5s9ds6sbjj.gif