Grub gone after reinstalling windows

Hi,

I had a system with windows xp on c drive and ubuntu installed within windows in g drive.
Then i reformatted c drive and reinstalled xp
Now i don't get the grub.
I tried the standard solution of booting from live cd and then sudo grub, root (hd0,0), setup (hd,0).
Gives error 17: cannot mount selected partition.
How do i know which partiton my ubuntu was in (if not hd0) ? And what should i do to restore the grub?
Thanks