If these Troubleshooting steps don't help, then You'll probably going to have to start looking at data ms project recovery tool, as Project Recovery Toolbox because it sounds like the header is corrupt. http://www.oemailrecovery.com/project_recovery.html
I have tried it and you too could see...
Follow to the next steps:
Save the file in the Microsoft Project Database format:
1. Open your problem file (it may help to turn off automatic calculation if the file is reluctant to open).
2. Select File/Save As...
3. Save as type: Project Database (*.mpd) then click Save.
4. Close the...