While testing various options in Grub menu, the system broke – it booted into a blank black screen. I had to use an Ubuntu Live CD to rescue the system.
Steps to Use Ubuntu Live CD to Rescue Grub Problem
- Boot up the computer with a live Ubuntu Desktop CD with option “Try Ubuntu without Installing…”
- Open a Terminal window with CTRL-ATL-T or click on application -> terminal.
- Use “sudo fdisk -l” command to figure out your drive designation. The hard drive on the messed up computer was sda5.
- Mount the hard drive to mnt with command: sudo mount /dev/sda5 /mnt
- Mount other necessary directories:
sudo mount --bind /dev /mnt/dev sudo mount --bind /sys /mnt/sys sudo mount --bind /proc /mnt/proc
Set root to new mnt directory:
sudo chroot /mnt
- Verify that the /boot directory is the working one by checking to see if there are lots of recent .mod files.
- Now to you can modify the /etc/default/grub file as normal.
- Update the grub configuration with command: sudo update-grub
That’s it. You can reboot the computer with updated grub files.