The most common problem is low refrigerant (freon). If you don't have gauges to check the pressure of your refrigerant, do this: the compressor has one small line running to the coils on the top of the freezer. That small line should be hot enough to burn your finger if you touch it when the compressor is running. Also the big copper tube running into the compressor should be cold to the touch, almost freezing. If not you are probably low on refrigerant. Without gauges and the ability to buy freon, you will need to hire a refrigeration repair service to find the leak in your system, repair it and then gas it up. But there are a couple of other things to check first. Near the compressor is a radiator like set of coils in front of a fan. If the compressor is running that fan should be running too. if not, the unit won't cool. Also the radiator coils may be covered with dust or grease. You must have a good flow of air through these coils to dissapate the heat put out by the compressor.If it is stopped up, brush the dust from the front of the coils. Look inside the freezer as well and make sure the inside coils are not frozen over. Is so unplug the unit and let the frost melt off. If that is happening you may need a new timer on your drfrost system.