Help Me Get My Life Back -- ALL of My E-mails, MIDIs and Photos Back!!!

I turned off my computer manually this morning (just pressed the button). when I turned it on this pm, the computer suggested the hard be checked. when that finally finished, I entered thunderbird. I had no e-mails, folders, or e-mail account. I was prompted to open up a new e-mail account. I lost MIDI files, photos, all sorts of treasured stuff. I don't dare start up a new account least I permanently lose all those e-mails. Is there a way I can get all of them back? Help!!!