Corrupted save file after forced steam reinstallation.

[Packed]

I have a bug with my steam client that randomly loses a game's location and forces me to "reinstall" them, even though it actually just finds the file locations again.
The same bug happened with Factorio and upon starting the game, my main save pops up with a prompt saying:
"Opening zip C:/Users/[my name]/AppData/Roaming/Factorio/saves/[my save name].zip failed: Bad zip file"
This issue doesn't seem to be happening with any of my other worlds and I was just wondering if there was any way of fixing it, or if it was 100% screwed.

[Loewchen]

You have multiple file corruptions not bugs. Make backups of your important stuff while you still can and check your drive for defects.