Cut everything off for a few minutes then turn it back on and listen for a click from the compressor relay as the compressor tries to start.
Is the compressor motor running.If no check starter/overload relay.
Check to see if the condenser fan at the back underneath near the compressor is running. If no check fan.
Are the condenser coils near there warm or room temp. should be warm
How to check stuff>
Refrigerator Repair Guide: How To Fix a Refrigerator - ACME HOW TO.com
Is the evaporator fan in the freezer running. It blows cold air into the fridge side through a damper in the wall between the freezer and fridge. Make sure the damper is open.
Below the evaporator fan is the evaporator coils. Remove the back cover in the freezer to observe the frost pattern. Light frost everywhere(NORMAL) or a partial pattern of ice(LOW ON FREON) or nothing(LOW FREON OR COMPRESSOR PROBLEM).