Reference:
Ubuntu boot up with GRUB Rescue> Terminal mode repair methods: http://www.linuxidc.com/Linux/2012-07/65249.htm
Windows& Ubuntu double system a key Ghost, prompt grub rescue solution: http://www.linuxidc.com/Linux/2015-01/111189.htm

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Windows 7+Ubuntu14.04 dual system has been installed, a Ubuntu14.04 has been installed, the following error occurs after boot:

error：no such partition
Entering rescue mode...
grub rescue>

has been reinstalled in the system before, so this problem has been encountered several times. Record it today

There are not many commands available in this case, ls, set, insmod

Enter LS and the following information appears:

(hd0) (hd0,msdos7) (hd0,msdos6) (hd0,msdos5)

this information should be the disk partition information, the mode is approximately (hd0,msdosX), X represents the number

Enter SET and the following information appears:

cmdpath=(hd0)
prefix=(hd0,msdos8)/boot/grub
root=hd0,msdox8

 

To find out which partition Ubuntu is installed on, here’s how:

ls (hd0,msdosX)/grub  OR  ls (hd0,msdosX)/boot/grub

enter the above command in turn, X is the number, is the ls command appears in the number, if there is a lot of file information, is the partition

Assume that the input LS (HD0, MSDOS4) is a lot of information. Next, set:

set root=(hd0,msdos4)
set prefix=(hd0,msdos4)/grub

Note: If /boot/ GRUB is above, change the following command accordingly

After setting, you can input set command to view, and the output information will change to:

cmdpath=(hd0)
prefix=(hd0,msdos4)/grub
root=hd0,msdos4

 

Continue typing the command:

insmod normal

This works for me or

insmod /grub/normal.mod

Or change to the corresponding /boot/grub/…

Finally, enter:

normal

Grub’s boot menu is restored

After entering Ubuntu, enter the following command:

sudo apt-get install grub2
sudo update-grub
sudo update-install /dev/sda

restart, return to normal