Please read the third paragraph first (I am more worried about that problem)

I recently made a plane and tried to load the level (to test fly it) and it said the game crashed. It then asked if I wanted to save my most recent changes as an aircraft named Backup-1 and when I did, I tried to load it, and it said that there was an error loading the aircraft. I then tried loading the latest version saved before that, and it said there was an error in that too. I then loaded the last version before that, worked on it, and saved it. When I tried to load the last version I had worked on to see if it worked, it said there was an error on that too.

I than looked up how to recover the lost version (Backup-1) and someone said Here that they were able to copy the aircraft XML file and paste it over the old version and recover the lost version -see Here how to get to the aircraft files-, and when I did that it said that there was a problem loading the aircraft, and then it said there was an error. I then tried pretty much all the other ways I could think of on how to get the XML files to work, and it wouldn’t work.

The next time I started working on something else (a B-2), I saved each major change twice under different names. I then tried to load the level to make it re-center in the sandbox, and I could see it on the runway, but when I exited the level, I could not see my aircraft anymore. It still shows all the information about the aircraft (weight, fuel, length, wingspan, etc.-like this:) as if it is still there- it just won’t show it. When I loaded the level again, it shows this:
I then tried loading the DesignerSuite blueprint I was using, and I wouldn’t show up. I then made a new aircraft to see what that would do if I then pressed undo, and the blueprint showed up. Like this:

So if you have any ideas on how to recover it, prevent it from happening, or what happened, PLEASE let me know!!! I will be very grateful. Thanks!