If you upgraded to Ubuntu Saucy Salamander, your phpMyAdmin won’t probably work more.
To get working your phpMyAdmin back, just execute the following commands:
sudo ln -s /etc/phpmyadmin/apache.conf /etc/apache2/conf-enabled/phpmyadmin.conf sudo /etc/init.d/apache2 reload
The reason why it doesn’t work more in Ubuntu Saucy Salamander is indicated on that webpage: https://help.ubuntu.com/community/phpMyAdmin#line-40.