My side by side fridge and frezer is working all right then all of a sudden it will not be working for a couple days then it will be all right. I don't understand why can anyone help me? Frezer seems only to work in the bottom shelfes.

Call a repairman. There are too many unknowns here. Could be any of a number of problems. Defrost timer, defrost tstat, defrost heater, condenser fan, etc, etc. I don't even know the make or model.