We had a missing door for fridge and made one.
If you have photos of the door as a general guide then most body shops and even ac shops can make one.
Difficult part is if it is a vented door as then it is not just a flat panel but then like the above photo it can be a simple frame with cross bars of z stock added.
There are salvage yards as well so search forum for rv salvage to go that route.
But a flat panel door can be easily made for not much money.
Find another user who can supply photos and dimensions will help.
Tony & Lori
1989 Country Coach Savannah SE