Recover Grub 2 via LiveCD
*
First, grab a copy of the latest Ubuntu LiveCD and boot it.
* Open a terminal and type
# —————————————-quick recovery begin———————–
# $ sudo fdisk -l
# $ sudo mount /dev/sda1 /mnt ##注意使用 你的 root分区所在的位置，也就是 / 所在的分区，可以使用 Ubuntu自带的磁盘实用工具查看
# $ sudo mount /dev/sda2 /mnt/boot ##如果有专用的启动分区的话 挂载它
# $ sudo mount –bind /dev /mnt/dev #这3个 比较必要，参数不用改
$ sudo mount –bind /proc /mnt/proc
$ sudo mount –bind /sys /mnt/sys
# $ sudo chroot /mnt
# # update-grub #已经是root了
# # grub-install –recheck /dev/sda #一般一块硬盘的话，不用改了
# # reboot #重启 就可以了
Restore GRUB2 – Recovering from a Windows XP / Vista / 7 Reinstallation
Fire up a terminal from the Live CD for Ubuntu 10.04.
$ sudo fdisk -l (Note the partition number on which Linux resides)
$ sudo mount /dev/sdaX /mnt (Replace X with the partition number housing Linux)
$ sudo grub-install –root-directory=/mnt/ /dev/sda
$ sudo update-grub
$ sudo reboot
Credits to
http://mundogeek.net/archivos/2009/12/08/recuperar-grub-2/ for the enlightening post &
http://www.webupd8.org/2009/12/how-to-recover-grub2-linux.html for the awesome translation.
重点推荐 Ubuntu Grub2 完全手册：https://help.ubuntu.com/community/Grub2#Reinstalling%20GRUB%202