I just replaced the “PTL” hinge at the top of the door.
The way it works is that the scissor hinge at the top extends and locks when you open your door all of the ways.
To close it, you have to open the door handle (inside or out) which pulls on a cable that runs up to the hinge and releases it so the door can close. If you look up on top of the door there are 4 screws holding the bracket to the door, one screw holding the clamp for the cable to unlock the hinge and a few screws holding the bracket to the chassis. If mother nature took off the hinge, order a new one from FT after you look at the underside of the bracket on the door. If the cable still responds to the door handles, just replace the hinge. (All I had to do to mine). Now if the cable is the problem (which might be why someone removed the hinge (because you have no way to unlock the hinge and close the door), you are going to have to take the door apart and fix the cable mechanism first. Luckily, mine was just a hinge and it was a five-minute job.