What operating system are you using? The layered PSD file is buggered and you'll be lucky to recover the layers, but there are PSD recovery tools out there. I can't say as I have ever heard of them being successful though.
Try opening in something like Ifanview. That might be able to read the flattened JPG that PSDs hold. You have two chances in that respect. The smaller flattened thumbnail, but you might be lucky and get the full size flattened composite.
Good luck — you are going to need it.