Running php scripts on apache in your Ubuntu desktop won’t be sweat at first. You might notice that php scripts start downloading when you start accessing them via browser. This is mainly because of small configuration issues that we can find on machine. If you have enabled userdir module (http://localhost/~yourusername), it contains a line to disable php values as follows in /etc/apache2/mods-enabled/php5.conf :
php_admin_value engine Off
All that you have to do is to disable the above line and restart apache to get php working.