If your grub fails to identify the location of boot files in your
system, you may confront a ‘grub rescue’ black screen. And thus your OS
(mint / ubuntu) fails to boot.
[Please note that, if you happened
to format your boot partition accidentally, then this technique won’t
work for you. The only possibility then will be relying on backups
previously made, or re-installation of OS.]
So on grub rescue mode you will be seeing a black screen with :
Code:grub rescue>
You need to type: ls
Hit ENTER
Now it will show,
Code:grub rescue> ls
(hd0,4) (hd0,3) (hd0,2) (hd0,1)
These
show the list of hard disk partitions you do have. Any one of these
might contain your boot file information for the grub. So we need to try
each of these, one-by-one.
So type Code:grub rescue> ls (hd0,4)/boot
If the one you chose is the boot file partition, then it will show,grub rescue> ls (hd0,4)/boot
... some kind of 'not found' message
And if the chosen one is your boot partition, thengrub rescue> ls (hd0,4)/boot
... grub ... initrd.img-2.6.32-33-generic ... vmlinuz-2.6.32-33-generic
To manually boot from the ‘grub rescue>’ prompt . Type Code:grub rescue> set root=(hd0,4)/boot
grub rescue> insmod linux
grub rescue> linux (hd0,4)/boot/vmlinuz-2.6.32-33-generic
grub rescue> initrd (hd0,4)/boot/initrd.img-2.6.32-33-generic
grub rescue> boot
Now you will boot without the grub rescue prompt.
After booting to Ubuntu / Mint
Open TERMINAL (ctrl + alt +T)
Type Code:sudo grub-install /dev/sda
And you are done