I had ubuntu 11.10 installed and I was upgrading it to Ubuntu 12.04.1. While upgrading my computer got shut down due to heating issues. Afterwards its not starting up and gets stuck at a black screen. I can use ctrl+alt+f1 to go to command line. But I dont know how to resolve this issue from there. It shows me a message the ubuntu release 12.04.1 is available and run the command "do-release-upgrade" to upgrade to it. But when I run this command, it errors out saying "no new release found". Can anyone suggest what to do ?