Howto Reinstall Grub!!!

It being a very common problem and sooner or latter a Linux user tends to face it when installing Windows after Linux… The master boot records from the memory are lost and they are writed for windows only systems…. So here is the way to write Master boot records or rather installing grub again so that LINUX gets back to work..

1. Boot the Desktop/Live CD of linux.
2. Open a terminal (Applications -> Accessories -> Terminal)
3. Start grub as root with the following command :
sudo grub

4. You will get a grub prompt (see below) which we will use to find the root partition and install grub to the MBR (hd0,0)

[ Minimal BASH-like line editing is supported. For
the first word, TAB lists possible command
completions. Anywhere else TAB lists the possible
completions of a device/filename. ]

grub>

Type the following and press enter:
find /boot/grub/stage1

Using this information, set the root device:
grub> root (hd0,1)

Install Grub:
grub> setup (hd0)

Exit Grub:
grub> quit

5. Reboot (to hard drive). Grub should be installed and both Ubuntu and Windows should have been automatically detected.

6. If, after installing grub, Windows will not boot you may need to edit /boot/grub/menu.lst (That is a small “L” and not the number 1 in menu.lst)

* Open a terminal and enter :
gksu gedit /boot/grub/menu.lst
Or, in Kubuntu:
kdesu kate /boot/grub/menu.lst
Your Windows stanza should look something like this :
title Windows XP/Vista # You can use any title you wish, this will appear on your grub boot menu
rootnoverify (hd0,0) #(hd0,0) will be most common, you may need to adjust accordingly
makeactive
chainloader +1

Best Alternative:

If their is a problem with grub or u want to make this still easy u can reinstall your grub by a application known as Super Grub Disk iso Image..
Boot your system using the disk and follow the instructions…