I had a look at your saves. Unfortunately the _Backup consists completely of NULL-Bytes and the other save is mostly NULL-Bytes. Because the country and date information from the save is lost, eu4 can't display it in the save games list. There isn't enough information left to even attempt to manually recover the save.
Such save game corruption happens occasionally, but I have not seen it in a while so I'm curious which version you are playing.
Unfortunately I don't really know why this is happening, so I can only recommend that you manually create additional backups of your saves so that you have something to which you can go back in case it happens again.
Disclaimer: I'm not working for Paradox. I'm just trying to help people.