Experiencing a cooling problem with your fridge can be incredibly frustrating, but getting it fixed doesn't have to be. The first thing to do is to get a sense of what and where the precise problem is, since there are a number of parts that might have broken down or malfunctioned in some way to cause a cooling issue. Once you know the source of your fridge malfunction, you can take appropriate steps to deal with it, from ordering refrigerator repair parts and installing them on your own to calling a major appliance repair expert for help.
If you have a refrigerator cooling problem, there are a number of visual checks you can perform in order to find what kind of refrigeration repair work you need. You can check if something is blocking one of the fans (there's usually a condenser fan on the bottom of the fridge and an evaporator fan in the freezer). If there is, then that means the whole mechanism isn't getting the airflow it needs and is probably overheating and therefore shutting off. You can also look on the back of the fridge at the condenser. A dirty condenser will cause overheating in the refrigerator mechanism, which in turn causes the compressor to cut out momentarily until things cool to a safe level. However, when this cutting off and turning back on happens continuously, consistent cooling is compromised. A third place you can look is the freezer. If there's excessive frost buildup in the freezer, it can signal a number of different problems with the defrost heater, the defrost thermostat, or the defrost control, all of which will affect the overall cooling process.
If you know a lot about appliances and are comfortable checking out your fridge cooling issues on your own or with the help of a refrigerator repair manual, it's possible to address some of these problems by yourself. Ambitious DIY enthusiasts can certainly fix a blocked fan or clean the condenser coils to get the refrigeration system back in working order. Tackling the electrical components involved in the defrost heater, thermostat, or control is a little trickier, however. Unless you already have appliance repair and electrical systems expertise, these may be solutions best left to major appliance repair experts. In any of the above situations, if you're unsure of how to go about the diagnostic or repair work, do call a refrigerator repair professional for assistance. It's much better to get cooling problems fixed quickly and safely than to try to do it on your own if you're not sure how to go about it.
Fridges can stop cooling properly for a number of reasons. If you find that your food isn't staying cold enough or is spoiling even though it's supposedly refrigerated, make the visual checks outlined above to try to discern what the issue is. It may be a problem that you can see and fix on your own, like cleaning a dirt condenser.
However, if it's something more involved, like a faulty thermostat, your best bet is to call an appliance repair expert. Whether you do the work on your own or call a professional, the most important thing is to get your fridge back in working order.