do I need a compressor?

My fridge/freezer has stopped cooling, I took the panel off the back and can hear a clicking noise. What is wrong?

The start relay is bad but there is a slight possibility the compressor may have caused the start relay to go bad. I have found that well over 90% of the time the start relay will fix this problem so start with that. http://www.appliance-repair-it.com/refrigerator-not-cooling.html