1. Look where linux is installed (eg: /dev/sda1, /dev/da2, etc).
If you don't know where your installation is type: GPARTED or type sudo fdisk -l to see your partitions.
For this example we will use /dev/sda9/ as an example.
2. sudo mkdir realroot
3. sudo mount /dev/sda9 realroot
4. Finally, copy this line as is: sudo grub-install --root-directory=realroot /dev/sda
5. That's all! :D
