I have installed Windows XP (hd0,0) after installing Ubuntu (hd0,1). Because of that my Grub2 loader is missing. My PC only boots with Windows XP loader. I’m looking for an easy method, which can drive me to boot (Windows XP and Ubuntu) from Grub2.
1.) Boot into your sytem via a LiveCD, though any distro should work fine. This guide assumes you'll be using a Debian based (Ubuntu, Mint, etc.) system.
2.) Install boot-repair and follow these instructions either by install or by burning their LiveCD.
Recovering Ubuntu After Installing Windows
Guide to Dual Booting Windows and Ubuntu (for future reference)
a similar question was asked a few months ago and it might solve your question. Please check it out and let us know:
Where did my Ubuntu partition go after re-installing Windows XP?