What the title says...

Have just lost an already installed Skyrim in Steam just like that, so now I need to reinstall the game plus my current game is probably ruined. Skyrim was detected as installed game earlier today and yesterday. So what's wrong?

Is there anything I could do to bring it back and don't tell me to contact Steam support, because I'm to angry and furious about what happen. Have anyone experience the same thing as I did today?