PHP doesn't "Fire". It's not a daemon or application that runs in the background. It works on the fly, processing the embedded code. I guess to get your webserver running again, you need to change the ServerRoot back to /usr.
Create an index.html page with the following code:
Place this index.html file in the directory that is specified by the "DocumentRoot" directive in your httpd.conf file. With a web browser, visit that index.html page, i.e. http://localhost/index.html
, or however you connect to your webserver, and see if you get all the PHP info, parameters, etc.
If this doesn't work, try to change the line that reads:
LoadModule php5_module modules/libphp5.so
LoadModule php5_module lib64/httpd/modules/libphp5.so
Restart apache, and try to visit the index.html page again. Let me know if either of these work.
Did you compile Apache for use with PHP, and did you compile PHP for use with Apache, or were these RPM or similar packages that you installed? They may not be working together properly.
If you are not comfortable compiling from source code, there is a package called XAMPP that is a standalone Apache webserver with PHP, Perl, and MySQL that may be easier for you to use for testing, until you can get your Apache/PHP installation straightened out. The website for XAMPP is http://www.apachefriends.org/en/xampp.html