Minecraft Forums

I went to play some minecraft, when I saw a message telling me to open my inventory (to get achievement). I was wondering why, when I suddenly realize my achievements and stats had been reset. I have not went into the .minecraft app folder to change anything or add/remove mods, textures, or worlds. Since I'm going to assume I can't ever get my stats back, does anyone know what caused this to happen or why? Thanks for the help.