My apologies, but if you closed down your game normally, you've most likely been a victim of the dreaded Steam Cloud Save bug.

You might be able to retrieve an older save from either here:
https://store.steampowered.com/account/remotestorage

...or here:

It is highly recommended to turn off the Steam Cloud Save feature FIRST, then move your recovered character and world to here:

Move your character file into the "characters_local" folder (if present, otherwise create it), and the world files into the "worlds_local" folder.

It is also HIGHLY recommended to do periodical backups of all your data. Shice can happen and data can get destroyed. External hard drives are cheap. Even a USB stick will suffice.

Good luck restoring your save file!