actually I was updating from ubuntu 12.04 to 12.10 suddenly my machine got switched off then when i restarted the machine I am facing the following problems: 1. Even after doing shutdown it is not getting completely off. 2. I cannot update anything with update manager it is showing "Check Internet Connection" where I have a 15mbps broadband. 3. whenever I am trying to update using update manager it is telling me not all update are installed the when I am doing partial update it is showing a error message as follows:
failed to fetch http://in.archive.ubuntu.com/ubuntu/pool/main/m/mesa/libxatracker1_9.0.3-0ubuntu0.1_i386.deb
then when I am doing do-release-update it is showing no new releases. so I want to return back to ubuntu 12.04