I used apache 2.2.4 webserver in my server and it uses su_php but I mistakenly deleted http-suphp.conf file and my website doesn't run. I searched for any solution but I got nothing. the path of su_php in my httpd.conf file is :
conf/extra/httpd-suphp.conf
as jon stirling has mentioned you can take the file and save it in the correct folder and restart your web server...
that file has some parameters you can patiently read and edit/tweak to your liking...
and no, you don't have to reinstall..(again i am assuming its your linux machine)