How do i recover a corrupted pages 09 document - "The document does not have a valid file format"
I was reverting a document when my computer froze. After I restarted, Pages was unable to open the file. I recieved "The document does not have a valid file format" notice. I'd been saving versions but can't seem to access them without opening the original document file. Is there some way to recover the text or is it gone for good? I can still see the Pages document and it appers to be the right size. Anyone know of any tweeks, recovery software, etc. that could help me?
MacBook Pro, Mac OS X (10.7.5)