# use fdisk -l to see your kali linux root partition. Example /dev/sda3
#change /dev/sda3 for your kali root partition
Code:
fdisk -l
mount /dev/sda3 /mnt
mount --bind /dev /mnt/dev
mount --bind /proc /mnt/proc
mount --bind /sys /mnt/sys
chroot /mnt
apt-get install grub2
#The grub2 package will be installed on the kali partition.
#When apt finish the instalation ask you for the partition to install grub2, select /deb/sda with spacebar, press tab, and [ok].
#Now you will see grub detecting your partitions and the installation finish.
#Reboot and have a nice day.