i need the code which will add default thumb, if there is not featured image available. I was using default thumb plus for this but this plugin is using a lot of resource so i need to remove it.

I was trying to follow this tutorial

But no luck. Inside my widget i have this code

<?php if (  (function_exists('has_post_thumbnail')) && (has_post_thumbnail())  ) { ?>

Edited : And whole code you can see here pastebin.com/715evL1E

Any idea how to this ? thanks