The evapoator coil is probably frozen up. Check it and see. If it is,
unplug the box and let it sit with the doors open for a day or so until
it is all thawed out, the plug it back in and see if it starts working.
If so, you probably have a problem with the defrost timer, defrost
thermostat, or heater. You may get also lucky and find that the drain
from the evaporator is plugged, causing the coil to ice up, depending n
the design of the box. Good luck Larry