Have a look in /etc/http/conf.d for a file called php.conf. If you don't have one, create it and put this in it:-
Code:
#
# PHP is an HTML-embedded scripting language which attempts to make it
# easy for developers to write dynamically generated webpages.
#
LoadModule php5_module modules/libphp5.so
#
# Cause the PHP interpreter to handle files with a .php extension.
#
AddHandler php5-script .php
AddType text/html .php
#
# Add index.php to the list of files that will be served as directory
# indexes.
#
DirectoryIndex index.php
#
# Uncomment the following line to allow PHP to pretty-print .phps
# files as PHP source code:
#
#AddType application/x-httpd-php-source .phps
If that fails, you could always visit
http://www.apache.org.