Hope I'm not repeating something, that someone else already said, but I thought it would be of value to mention, that if you have Win 7 or XP, on the same PC and it will boot, you could use grud24dos.

Install it on the MS OS and then you will have a "virtual grub", that you can use to boot into any other OS that you lost, and then follow the usual procedures to restore grub from your other OS.

No need to boot from any other media.
No need to write to the mbr.
No need to burn discs.
No need to download isos.
Grub will be compatible.

and I'm sure there are a bunch of other good reasons.