Corrupted world file

My worlds keep getting corrupted why is this happening. I have almost 100 hours on tModLoader now. Basically I play a world a few days it gets corrupted and the backups won’t load then i start again this has happened to 4 of my worlds now. I am getting fed up of it. Everyone keeps saying “just replace it with a back up” but that isn’t working. I try to delete the corrupted save and replace it with a back up and the world just disappears from my tModLoader. What can I do?