I am stuck at grub rescue. I tried booting Ubuntu from a live USB, then doing this
sudo app-apt-repository ppa:yannubuntu/boot-repair
the this error came up.
Please check that the PPA name or format is correct.
You are using the wrong command(s) - the correct ones are :
sudo add-apt-repository ppa:yannubuntu/boot-repair sudo apt-get update sudo apt-get install -y boot-repair && boot-repair
Note : When you really deleted the Ubuntu system partition, you better should reinstall Ubuntu.