My save file is gone.

[muppetmuffins]

I had about 19 hours in the game, and saved at the playground. I opened the game and everything's gone, dunno what to do.

[LV-04 "Leelee"]

Your saves are in Steamapps\common\OMORI\www\save you may be able to restore your own save files it's a move that I recommend trying before downloading others:
Rename your file1 (or whichever your main latest file is) to something outside of the game's reach like file7 just for extra safety, then start a new game just to make a new save in-game in slot 1 and while the game's still running, delete it, rename file7 back to file1, then you might be able to reload slot 1 unless it's completely broken for sure.