I'm having the same problem with my MySQL on Ubuntu 11.10. Everything worked fine until I rebooted my pc now I can't login to phpmyadmin, the mysql has stopped responding and my site (installed locally) is offline.
I tried rebooting mysql (/etc/init.d/mysql restart) but this doesn't work, I also tried editing the /etc/init/mysql.conf file but this doesn't work either.
Does anyone know of anything else I can do to get this working again?
Also I didn't back up my database in phpmyadmin, in case I can't get back in is there any other way to access the database?