I dont know if this is a bug or not but my minecraft account is gone. I was playing and then logged off to change my cape and when i came back my only profile was demo and says i havent bought the game.

I logged of Minecraft to change my cape.
When I launch the launcher it told me to log in. while I was logging in it said invalid credentials and then deleted my profile and now I only have a demo version.
I thought I would just go back into MC with my new cape.