You can boot a linux live CD to get the files that you need of the drive (Puppy Linux, Parted Magic, Slax, ...).
You can build a Windows PE disk to access and recovery your files (like UBCD4WIN).
Or you can remove the drive from the PC and put it temporarily in another PC (which has a working system disk).
Did you try a blank admin password (just enter)?
You can build your own Recovery Console with Jaclaz "no CATCH 22" (no admin password needed):
http://www.911cd.net/forums//index.php? ... ntry141854
A tool that can create such a Recovery Console:
http://www.msfn.org/board/install-usb-a ... ntry881045
Download Ultimate Boot CD v5.0
Use Parted Magic
for handling all partitioning task: http://partedmagic.com/