I am afraid not.
Anything you can do can potentially delete things to beyond recovery.
The only safe option would be to borrow XP or a vista CD and then boot to safe mode
and run fixboot.
I would suggest another option (if you are a type of person who is okay taking risks).
If you have any other system where you can download from internet, then,
you can use this
download and burn it in a CD and boot from that CD.
This will show you and help you boot from the harddisk even of the MBR is not working (assuming
that the Vista bootloader is still intact in its own partition )