Geoff: I think aljasdolfdjododl's ISP isn't allowing overrides like that in the main httpd configuration file, so he won't be allowed to do this.

Aljasdolfdjododl: I think you'll need to establish just what does and does not work in terms of PHP file extensions on your server. The tech support desk at the ISP and / or their FAQs may help, but more likely they won't know. Put a file called testing.php in your document root (i.e. home directory for web pages) which contains:
<?php phpinfo() ; ?>
(yes, just that 1 line) and point your browser at it:
http://yourdomainnamehere/testing.php
If you get nothing, or (when you view sources in your browser) you just see the phpinfo command, your PHP has not worked. If you see a complete configuration report from PHP, then - hey prosto - you know what extension to use!

If the first test does not suceed, then try extensions .php, .php4, .php5 and .phtml; I've seen all of these in modern use. You'll need to rename or re-upload the file AND change the URL that you browse to.