hello,
i have a dual operating system in my system the linux boot loader is default boot loader. Grub has been curropted and i am unable to access even windows operating system also.

Which distro do you use ?
Did youŕe install media has a rescue mode.
If so we can try to reinstall GRUB
If it
has no rescue mode do you have a linux rescue CD
If you do have one of the two options mentioned above
The next commands at the rescue mode will do
chroot/mnt/sysimage
grub install /dev/sd?
sd? being the place where you have install GRUB in the first place

Like ronlau9 says, without knowing what Linux distro you use, it's hard to get too precise with an answer.
Mepis, for example, has a boot repair "System Assistant" on the LiveCD:
http://sblinux.org/mepis_manual802/i...#section05-3-2

With other distros you may have to reinstall GRUB using a command line interface, like he suggests. You're going to need to have a LiveCD of some Linux OS just to get the machine booted so that you can do the job.

Getting the machine booted from a LiveCD is the first step.
Fixing GRUB is the second step.

As long as you have a LiveCD, the problem should not be a great one. Unless -- there may be problems with the Hard Disk Drive that go beyond GRUB.