first thing is you need to read about installing GRUB manually by reading
just boot with live cd and open a terminal and as super user or sudo grub .
then in a terminal 'sudo grub'.
This is the link to the GRUB manual that will explain how to install GRUB. Using grub-install is less safe than installing GRUB natively.
read more here:
**www.gnu.org/software/grub/manual/grub.html#Installing-GRUB-natively
be aware of ur partns,ie your root partn number etc.. use setup(hd0) if u install grub into MBR
for finding partn names use "fdisk -l"