There is always a reason for something like this to happen...but finding the explanation is never easy. That sucks...my recommendation [which is what I do in this situation] re-do the whole thing. It sucks really hard, but I think that's the quickest way to get it back usually.
Damn! I really wish i had an answer for you on that one. I really do. But i'm at a loss. There could be so many possibilities to what happened to your MMS page. There are 2 things i can think of to what happened: Either someone did in fact hack into your profile but why would they only mess with your MMS page and not post. And then the other thing is that, you could of accidently went into your profile one day and by mistake hit the reset button without knowing it and closed out your profile to post and then everything disappeared. That's all i can think of.