This appears to be a common problem on 12.04. I\'ve tried everthing in this thread including:
sudo apt-get clean
sudo apt-get autoclean
sudo apt-get remove
I had this problem many times. I can add an other piece of solution for this jigsaw...
WARNING: the following steps will delete your data! Do a backup first!
You have to:
rm -rf /var/lib/mysql rm -rf /etc/mysql
AND
Verify that, the interface "lo" is up and, the traffic is allowed on "lo" (iptables).
Hope that help someone else !