Grub Rescue In A Minute

First make a usb bootable of linux and 

use as try (live)the open cmd 

sudo mount /dev/sda5 /mnt *****Using the linux installation on your hard drive

//// instead of /dev/sda5
sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
grub-install /dev/sda *****Using your boot device instead of /dev/sda
CTRL-D
sudo umount /mnt/dev
sudo umount /mnt/proc
sudo umount /mnt/sys
sudo umount /mnt