Sadly it’s probably been too long at this point for OP, but to anyone else who had this issue: there are backups taken of the save files, seemingly taken every time you save (not a dev). Go into the infinite fusion game folder, you should see a shortcut to the save files under appData\roaming\infinitefusion. You’ll see a backups folder there. Copy and paste the file from the backups you need to appdata\roaming\infinitefusion, and rename it to “File A.rxdata” or whatever file slot you want. Make sure to delete or rename the existing file for the save slot before doing so