Save Files Keep Deleting For No Reason

Hi, I am a long-time player of Stardew. This is one of my favorite games, and I have put so much time and effort into one of my save files.

However, I have run into a very serious problem and I really would like advice on how to fix it. For some unknown reason, my game files keep getting wiped. I have no idea why this happens, but it has happened about six or seven times now, where I'll start a new game, play it for a while, then when I go to the "Load game" tab, my save file is just gone.

I've messaged several people in the past for this problem, but no one seemed to be able to help. The file of the game would just be empty, meaning my file got wiped overnight for no reason. Then, around June of last year, I seemed to have miraculously fixed the issue. I created a new save file, took old data from one of my "deleted" files, copy and pasted, and my game was restored! I was absolutely ecstatic, seeing as the several weeks I put into my game didn't have to go to waste. Everything was fine until this morning.

I pulled up my game, and saw my file was deleted again. I tried the same trick as I had done before, but this time it didn't work. I have all the data from my file, but everytime I paste it into a new file, THAT file gets deleted now. I don't know if it's corrupted or what, but if anyone is good at coding or whatever I'd be happy to send over the file info.

I really have no idea why this keeps happening or how to stop it. I had achieved so much in my game (had high hearts for nearly every villager, had a big coop and barn, horse, goat and cow and chickens and rabbit, Day Eight of Season Three Winter, was married with a child, gotten the sword from Calico Desert, and was on Qi's challange. I was just one rabbit's foot and truffle away from completing the recreation center)

I would really like some advice on how to solve this. It don't think I'd be able to start a new game from scratch after having put so much time and effort into this game. If anyone knows how to help, it would be greatly appreciated.

Thank you!