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.
I'd recommend you to use "boot-repair" which is a graphical program that lets you repair most grub-related issues such as yours.
Check out this guide on how to install it and use it to fix your bootloader. Although this guide is for ubuntu, Mint is based and completely compatible with ubuntu, so you are safe to follow that guide.
make sure to select your drive and your mint partition as your drive/boot partition