"LINUX RESCUE"

Suppose you have two Operating systems "Windows & Linux" in parallel.Somehow if windows becomes corrupted.Then what should you do?Reinstalling the previous OSs again is not the solution.Here is a solution.
If windows becomes corrupted then you should recover your previous grub-Boot-Loader.If you can recover it then you will be able to rescue your Existing Linux OS.

First you have to insert your Linux-Bootable disk.
And there type [linux rescue]
then there will appear some messages.
then type [/mnt/sysimage]
then [chroot/mnt/sysimage]
then [grub-install /dev/hda]

Thus this will install newly Grub-boot-loader to MBR(Master Boot Record)
Then type [reboot]
After a successful rebooting a boot-loader will be appeared.Then select the first Linux OS.And press'e' button.Here 'e' for editing.
then type exactly the following codes (without third bracket).
[ root (hd0,7)
kernel /vmlinuz-2.6.18-8.el5 ro root=LABEL=/ rhgb quiet crashkernel=128M@16M
initrd /initrd-2.6.18-8.el5.img ]
then press 'b' button to boot your selected Linux OS.