The first step for troubleshooting a refrigerator is to check the electrical connections, which power the cooling process and the lights. If the refrigeration fans don't run and the light doesn't turn on, the problem is almost certainly electrical.
If the problem is electrical, it's worth making sure the electrical cord is plugged in and not damaged. Refrigerators draw a significant amount of electricity, so resetting a tripped circuit breaker can solve the issue. Electrical problems within the unit, however, typically require expert help.
If the light comes on but the refrigerator doesn't cool, users can check their temperature settings to make sure they haven't been changed inadvertently. In some cases, obstructed air flow can cause the refrigerator to act erratically or to cease working at all. Removing items from the refrigerator and freezer can fix this problem. This also gives the user a chance to clear out excess ice, which can obstruct air flow and cause problems with the thermostat.
Compressors are common sources of problems, and a number of problems can cause the compressor to overheat. One way to test for overheating is to unplug the refrigerator for at least two hours. If the refrigerator starts running again once it's plugged in, the compressor likely needs to be repaired or replaced.