Fixing that some themes shows no featured image option

Some of the free reseller themes comes with the problem that after theme activation, the option to add a featured image in a post does not show.

The solution is simple. Just follow these steps:

1. Log in to your WordPress installation.
2. Go to Appearance > Editor.
3. Open the file functions.php
4. Scroll to the end and add this code just before the end php tag ?>

   add_theme_support( 'post-thumbnails' );