Ok some actual help:
- do not keep opening your project in editor, hopefully autosave with working level is not yet overwritten
- create backup of whole thing now (like zip, or just COPY it to another folder, and it better be not desktop folder!)
- then get some application that can search inside binary files, for eg TotalCommander can (mark autosave folder and alt+F7, then fill “search for text”)
- so when you have that search tool search in autosave for name of your level (case sensitive)
- and when you found such file see what it is inside and make sure it is your missing level, when sure copy over level in your project (you HAVE backups now?)
- if it was wrong file repeat find next one with name of your level hint: it should be similar size to what your level currently is (smaller by few kilobytes).
And get git, then github or gitlab. Do your backups with git, you do not need to push project to gitlab or github, just add changes then commit. OR at least make zips of whole project every day or after every major step.