If the questions are:

Is it possible to repair grub with different version of Ubuntu Live CD?

If possible then how could I do that and how risky that process?

The answers are:

Yes, it is possible and safe. It does not involve any risk to repair the Grub.

Should just do it through chroot:

Insert the Ubuntu LiveCD into the CD/DVD drive and reboot the computer. The machine boots from the LiveCD.

Click the “Try Ubuntu Without Installing” icon from the LiveCD “Start” menu. Ubuntu boots from the LiveCD.

Click “Applications” from the top taskbar in the Ubuntu desktop, and then click “Accessories.”

Click the “Terminal” option. The Ubuntu command-line terminal opens.

Type the following command at the prompt and press the “Enter” key. Replace “sdax” with the name of your “root” partition linux 8300.

sudo -i

fdisk -l

mount /dev/sdax /mnt

mount --bind /dev /mnt/dev 

mount --bind /dev/pts /mnt/dev/pts

mount --bind /proc /mnt/proc

mount --bind /sys /mnt/sys

chroot /mnt

grub-mkconfig -o /boot/grub/grub.cfg

grub-install --root-directory=/mnt /dev/sda

grub-install --recheck /dev/sda

umount /mnt

reboot