These links explain how door and springs are installed, and will help you figure out what is broken, missing, etc.:
https://www.rvworldstore.co.nz/domet...zer-door-parts
http://www.dyersonline.com/dometic-p...door-flap.html
After you determine part number(s) needed, Amazon.com, Camping World, or your local RV parts store can probably provide better prices and/or faster delivery.
Note: Look for little plastic parts and springs on the floor. They may be the ones that popped out when the door failed.
Also, if a corner hinge is broken off of the flapper door, it's possible that it can be repaired; and you may not need a new freezer door ($100+).
When ours broke, I solvent-welded several layers of polystyrene plastic (purchased at a hobby shop) to the broken hinge to repair it, and reinforced both hinges with the same material.
Please advise if hinge is broken, and I can provide detailed instructions on how to repair.