From everything I've read and understand, I don't think you can restore from that 3.1Gb file, unfortunately, not using restore from desktop backup anyway.
Moral of the story is always test your backup/restore process fully, before you actually need it.
You probably can do a reinstal of the OS and manually configure everything again. Then use WinRar or linux RAR to restore particular data files to the ibays etc.
Regards
Ray