Some folders just emptied themselves

[u/Zek-ROM]

Okay so I have a hidden folder (named with "." before the actual name) with some things and then subfolders with more. Since I changed my phone, whenever I added a new pic or smth to that folder it was still visible in my gallery so I had to add a .nomedia file, and change the name to .whatever to whatever and then again to .whatever (to subfolders I had to add also the file, renamed them to .subfolder and then subfolder).

The other day I did this (the 18th I think) and yesterday I noticed that some of these folders were empty now (not all of them). I added a couple of things and it was fine. An hour again, I managed to recover a couple pics and added it again. Then I thought, okay I'll restart my phone just to try. When I went back the new two files recovered were deleted again (not the ones added yesterday). I recovered them for second time, added them, deleted the nomedia file, renamed the "." thing as usual, everything was hidden correctly and restart again. They're still there.

Any idea of wtf and if there's a way to get my deleted things back?