Grub issues

I killed my grub a enough times that I wrote this "script" to chroot into my system from a live cd / usb

To chroot in to a system with lvm2:

yes | sudo apt-get install lvm2
sudo vgchange -ay big
sudo fdisk -l /sda
sudo fdisk -l /dev/sda
sudo mkdir /tmp/mnt
sudo mkdir /tmp/mnt/boot

sudo mount /dev/big/boot /tmp/mnt/boot
sudo mount /dev/big/root/ /tmp/mnt

sudo mount --bind /dev /tmp/mnt/dev
sudo mount --bind /proc /tmp/mnt/proc
sudo mount --bind /boot /tmp/mnt/boot

sudo chroot /tmp/mnt

Some things that might fix Grub:

nano -w /etc/default/grub

grub-install /dev/sda
grub-install --recheck /dev/sda

yes | sudo apt-get install --reinstall libdebian-installer4
sudo os-prober
sudo update-grub

Exit and unmount:

exit
sudo umount /tmp/mnt/dev
sudo umount /tmp/mnt/proc
sudo umount /tmp/mnt/
sudo umount /tmp/mnt2