I assume it's your water dispenser that's not working. Do you hear the solenoid behind the unit click when you push the switch for water. You can disconnect the water line coming out of the valve and try the water switch.
If that checks out ok your water line could be frozen in the freezer door. You can disconnect the line under the unit before it goes into the door at the bottom hinge. Push the dispenser button and see if it comes out there. If it does try a hair dryer blowing where the water line is at the dispenser for a few minutes. Raising the temp of freezer slightly might prevent it from happening again. | 
Water not flowing 
