Find the location of your php.ini is very easy if you know the way. Here are some methods to locate/find it.

Via Linux command shell / SSH

You can use this command to find the path to the php.ini file:

php -i | grep php.ini

It will return something like this:

Configuration File (php.ini) Path => /usr/local/lib/php.ini

That's your file!

Via PHP Info page

You can also see the location of your php.ini. You just need a PHP Info page.
Check this topic if you don't have any yet:
http://forum.xhanch.com/index.php/topic,692.0.html

You can see the location of your php.ini from Loaded Configuration File value