Refrigerator will not cool

Check the following:
Make sure the evaporator fan (inside fan) is working, then check to make sure the condenser fan (under the fridge) is working.
While you are checking, clean all of the dust off of the condenser, these are the black coils that are under/behind your fridge.

When you checked the evaporator fan, was the evaporator covered in ice? If so, then it will need to be thawed (defrosted). The evaporator can freeze for any number of reasons, the three most common are: a) dirty/blocked condenser coil, b) faulty defrost timer/element, and c) low on refrigerant.

Is the compressor running? If so, then double check all of the above, if everything checks good then you might be low on refrigerant, this is outside the realm of the average do it yourselfer, and a repair man will need to be called.

If the compressor is not running, we must determing why. Is your thermostat set to high? If not then check to make sure voltage is traveling through the thermostat.
I will admit, that this is a whole lot easier on commercial coolers and freezers than residential ones.
It could be stuck in a defrost.
Many things to check for. These are the most basic.

Thanks a bunch. I will definitely follow your suggestions ASAP!