How to recover lost progress...

It gone.

You might want to have a look at your HDD if files on it are getting corrupted.

chkdsk.exe is a good start.

Backup whatever is in your save directory to another location.
In Windows 7 saves are in C:\Program Files (x86)\Steam\userdata\[account number]\203160\remote
Delete what was in the save folder while keeping the backup handy.
Go to Steam, right click the game > Properties > Local Content and do "Verify integrity of game cache" and "defragment cache files"
While you're at it you'll want to disable Steam cloud for the game now (bottom of the Updates tab). This prevents it from trying to restore your last save from the Steam cloud server.
Put the backed up save file back. Should be named save1.dat or similar.
Restart Steam and try it out.

If it's still showing up corrupt you may want to nab one of these so you at least have a chance to finish.

I have a problem with Tomb Raider 2013 achievements that are pissing me off. I have finished it twice (from the beginning), also with the 100% complete, and I don't get the "a survivor is born" (complete the game) achievement.

So, I'm with you, bro

Just give it a day. Might start working again. Or not.

play from beginning again, always work.

not sure how steam files work
but it would be fun to have a database with save files at each level for a game or part/progress
i used to this long ago from gamefaq.com, they have game save files

well, i lost all my progress in machinarium and magicka, too. without any "corrupt file" or any other error message. it just has no game-saves anymore since some time. :(

yeah i know, this doesnt help you. me neither. just had to finally have my coming out here about this. have fun playing the game again ;)

If you were lucky, Windows made a backup for you. Look for the folder where the game saves are (don't own this one, thus I don't know where), right click it and choose "Properties", then go into the last tab (don't remember the name and not using Windows right now), there should be a list of the a few backups of the folder, pick one and restore it.

That feature saved my life quite a few times.