How to fix a GRUB Boot-loader that does not recognize a partition without a fresh install?

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http://askubuntu.com – I was running two separate partitions of Linux (Ubuntu and Linux Mint) and Windows XP when I deleted my Ubuntu partition through Easus partition manager on XP due to simple stupidity. This erased my Grub bootloader, but I managed to install Grub Legacy from my Linux Mint Live CD. However, I cannot access my XP partition, and when I try to update GRUB boot-loader through Linux Mint, I receive an error message. I cannot perform a clean install, so I need to know how can I fix my GRUB Boot-loader through Linux Mint, so that it can recognize my Windows XP partition. (HowTos)