Most likely door came open while traveling and was bent as it hit side of trailer. I had a similar problem with one I bought.
I made a template of the side of the trailer at the front of the door with plywood, then transferred curve to a 2x6 board. I placed board on outside of door at the latch, and placed C-clamps with small 2x4 blocks. I slowly tightened clamps until the door matched 2x6 template. this will bend the door. Release clamps and close door to see if it requires more bending.
If it does then cut 2x6 template curve a bit more ( mine required 1" deeper cut in the middle ) and re-apply c-clamps and blocks and slowly tighten again, work in small increments along center 1/3 section checking fit often.
My door had a glass window in it, I don't think your Argosy does. I used 6 clamps and alternated tightening of clamps from top and bottom to the center at the door latch. Do not place a clamp on door latch area.
Hope this helps.