Fable 3 taking me back to the start up screen?

I've had Fable 3 for a while now, and I was probably half way through the game. then all the sudden, i turn it on today and it takes me to the very beginning, asking if i'm a guy or a girl. its as if it doesn't have any of my saved data. which really sucks. any ideas on how this happened or how i could possibly fix it?