What happens when GRUB files in linux os?

Hey ,

I think you are trying to ask what if the GRUB fails?

 in that case, you can boot with a linux LIve USB/CD and chroot into the partition and re-install / configure grub.

Hope this is helpful for you.

Thanks,

Venkat

If this happens you may not be able to boot to your OS. You should use the Linux recovery dis and restore the boot-loader using the builtIN tool set. To access that press the <space-bar> or the down-se then boot menu  to select recovery mode. If you didn't make a backup of your /boot partition or /home then select build a new partition, because most likely the partition mgr has become confused as to where /boot/grub resides.

I think your question is wrong, please be clear.