I used aptitude install to install a package, Ubuntu 11.10 oneiric, that apparently I couldn\'t install because of dependencies. I removed a couple of more libraries while d
Try this
If you have added a line from new ubuntu repository to /etc/apt/sources.list, erase the line. Then, run the commands
sudo add-apt-repository ppa:marutter/rrutter
sudo apt-get update
sudo apt-get upgrade
It worked for me, the answer comes from here http://r.789695.n4.nabble.com/Upgrading-on-Ubuntu-from-2-11-1-to-2-15-1-td4636965.html