Check:
If the bulb is out or if it doesn't have one, see below.
If it has a door dispenser, see if it's functional.
Check fresh food side for lights working.
Check for power at outlet ( I say this last because it usually requires moving the refrigerator, which sometimes can be a pain). Test the outlet by plugging something else into it. Or if you already have some else there, see if it is working.
Do you have power to the outlet?
no - see HERE
yes - see next check HERE