Hmm.... I think I might know why you lost so much progress. Thing is right the game actually saves constantly, whenever you solve anything or go into a new room. If it's thrown you back that far it must be to do with Steam's cloud saving. The quick shutdown must have meant Steam went down before it could synch the new save file. Then when you reloaded it went back to the last time the cloud save was synched. That's probably my fault for trusting the latest cloud save I find is always the latest. That's gonna be a tricky one to fix. Will need to do something to check if the game's internal save data is newer than the cloud data.