php.ini location varies on OS.
in *nix environments its typically in /etc or /etc/php
in windows environments its typically in C:/php or C:/Program Files/php
If you are using a hosted solution (GoDaddy, etc) then you would not have access to the php.ini. However many of these hosted solutions allow you to create and modify your own php.ini. If this is the case please check with your hosting provider to see if they do.
