My refrigerator stoped cooling and freezing. The lights and the fan come on, but will not cool...

Hello,

The first thing I would do is remove the cover on the back of the fridge and check if the compressor is running. If it's not, then it could be the start device. Remove the power from the fridge, pull out the start device from the compressor and shake it. If you can hear something inside is moving, replace the start device.but if otherwise then,
Your defrost timer located inside the control panel is bad OR the defrost thermostat located on a freezer coil is bad.
Get down low and look up at the bottom of the control panel.
You will see a small round hole. Onside the hole is the defrost timer advance knob.
Use a flat blade screwdriver and SLOWLY turh the slotted knod clockwise until the refrigerator clicks off.
Wait a few minutes then open the freezer door and listen for a sizzling sound from the freezer compartment.
If you do hear a sizzling sound that would be the defrost heater melting ice.
If you do not hear a sizzling sound,unplug the refrigerator and remove the rear freezer panel to expose the cooling coil.
Clipped to the coil will be the defrost thermostat. It will need replacing.
If you do hear the sizzling sound the defrost timer will need replacing.

Good luck and hope this will work