I recently figure out the problem of supporting special characters in post or plugin.
I find this problem when i try to add the latin word it display ? as output. I googled a lot to conclude the problem has in 
/** Database Charset to use in creating database tables. */
//define('DB_CHARSET', 'utf8');
  /** The Database Collate type. Don't change this if in doubt. */
 //define('DB_COLLATE', '');
So I just commented this and checked it working. ŠĐĆČŽ When i again undo the comment it returns  ? mark. 
Which is the best way inorder to support special characters in wordpress post or page or plugin.
Thanks.
