Not sure if this question is still relevant (it seems it's pretty recent).
I ended up here having had the same issue (managed to deleted grub by wiping a harddrive).
I found the following link to be supremely useful:
Looks for section 13 "Reinstalling GRUB 2 from LiveCD".
In my particular case, I had W2K installed on my primary (boot) harddive, and installed ubuntu on a second harddrive later. As a result, grub was installed on the same drive that W2K was on - and allowed me to dual boot between the two.
I decided today that I could get rid of the W2K installation and use the disk space for something else. I stupidly erased the entire drive, including the bootloader...
I physically moved the disks around to ensure that the drive wth the ubuntu installation was the "primary" and used the steps at the link above to re-install grub... Bob's your uncle, I'm back in business.
Hope this helps someone.