I have a 5 year old refrig/freezer that is not staying cold. The refrig. Is at 50 degrees. Ice cream soft in freezer. Fan is working when I open the door and push the button in. Frost is on the back of the freezer. What do you think is going on?

If you have frost covering entire evaporator and both the evaporator and condensing fan motors are running you will need to check and make sure it is going through a defrost cycle, that the condenser and condensing fan motor are extremely clean. If all this checks out OK you could be low on refrigerant and will need to call a tech for this. Also check the door seal and make sure it is sealing properly