In my project simply I want to run local application as netbeans or word document installed in my computer on click of a link? Is it possible ? If yes how am I to do it? If no why it's not possible. Thanks in advance.
You can link to a PHP script and then in this script use exec() to run your application.
<?php
exec('path/to/your/app.exe -possibleparam -param2');
/* EOF */
I don't know if it is that what you are looking for: http://www.php.net/manual/en/function.exec.php
exec will execute the app in the machine where the php is installed (so your server). If you mean that the php should open an app on the user pc while he's surfing on your site, no.
The only way to to this is an NPAPI plugin. And use Javascript, not PHP.
PHP runs on the server. It has no control over the client. This is by design. If web pages could run programs on the client computer then it would be abused to an unlimited degree, for spam, viruses, and junk.
You can use the exec function to run a program on the server. If your server and client happen to be running on the same local computer, then this will do what you want.