Have you tried starting a brand new file? Maybe something just went wrong with that file and there isn't a way to save it. If you're still unable to move forward even if you've tried with a brand new file, definitely let us know.
Are you using build 1.1 or 1.0 (it's shown in the bottom corner of the main menu)? I might have an idea of what could have gone wrong, depending on which version you're on.
