Alright, so here's how the story goes.
I wake up in the morning to play some SK with friends and open it up through steam.
...
I find no steam login option, just the normal login with user/password option and login as guest option.
Could someone help me out with this? I'm really scared I lost all my data and will never be able to play again :(
Here's some images to show that the steam login option has COMPLETELY disappeared.
https://postimg.org/image/fpjtez3v5/ (login screen)
https://postimg.org/image/gn19kyfn5/ (option screen where the steam bar is shown at the top)
That's usually a problem with Steam (sometimes it's down or some other reason SK can't connect to it).
Try closing SK and Steam and logging back into Steam.
Your account isn't lost because if it were it would go to the introduction right away.