Today I had to fix two issues with my computer not booting through grub
bootloader.
One of the reasons was a failed installation of Ubuntu due to using an
USB stick with a corrupt image on it.
A little Google query found a page with info about boot-repair,
describing a great tool to fix grub boot problems.
I used the 2nd option, simply boot into a live Ubuntu installation and
run these two commands.
Then follow the steps given.
https://help.ubuntu.com/community/Boot-Repair
$ sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
$ sudo apt-get install -y boot-repair && boot-repair
