Blender file has size but empty

Hi, recently I am facing a huge problem when i am working on a project the next day i open it i find it empty with the default cube and camera but from outside it has the proper size and also the containing thumbnail what might cause that . i tried appending but it said file has no library. please if anyone could help cause there is many effort were lost and i couldn’t sacrifice more

Haven’t faced that issue before.
Can you check file data?

Also Recover->Auto Save may help restore the file.

It still doesn’t work. and unfortunately i don’t use autosave cause Iam dealing with big file sizes bit the backup file works fine but why the main file doesn’t?
It’s my first time to post here . how can i upload the file?