There might be able to find a backup with your save data.
You can find your save file at Your save file is named "minevar_v2.save".
There should be backups in the same folder.

First, i'd recommend making backups of all the files there.
Then, remove the "minevar_v2.save" file, then rename one of the backups to "minevar_v2.save".
Finally, launch the game. If your progress isn't restored, try another one of the backups.

I've had problems where the game progress was reset to an earlier state, both times because of Steam Cloud. i disabled it for this game to prevent it from happening again.
I do not know if this is what happened to you, but you can find your Cloud saves for this game here :
https://store.steampowered.com/account/remotestorageapp/?appid=1865060
(When "downloading" a file from Steam Cloud, you'll be asked to choose a file to replace, you might want to make some dummy file for this.)

If you want to check if Steam Cloud was the issue :
Check when the savefile was last synced. If it was before you lost progress, you can download it and try to launch the game with it.
If it's the blank save, then Steam Cloud would probably be responsible.