I was upgrading to a new version of Ubuntu 10.04 to Ubuntu 12.04. Suddenly my power went out half way through the installation, and it could not complete. On start-up I see versions of Ubuntu 18.104.22.168-generic, but when I select that it shows no disc found and Ubuntu screen stand still. I don't know how to solve this.
Is it possible to remove the existing install completely and install again?