downgrade php 5.5 to 5.4

gistfile1.txt

# upgrade system, so you can add to ignore all updates later
sudo apt-get update
sudo apt-get upgrade

# remove your php, apache, etc
sudo apt-get purge apache2 php5 libapache2-mod-php5 # add here your server packages

# change repositories to raring  (with backup)
sudo sed -i.bak "s/saucy/raring/g" /etc/apt/sources.list

# update and install server packages
sudo apt-get update
sudo apt-get install apache2 php5 libapache2-mod-php5 phpmyadmin #add here packages you need and make sure you install php5.4 and apache2.2

# change repositories back to saucy
sudo sed -i "s/raring/saucy/g" /etc/apt/sources.list

# lock versions
dpkg --get-selections | egrep '^(apache|php)' | sed 's/install/hold/g' | sudo dpkg --set-selections

Before you "change repositories back to saucy" make sure everything works for your site(s). Otherwise you'll have to switch repositories back to raring again to install anything else.