WordPress 3.5 Add New Media Not Working Solution: The New WordPress 3.5 Version has many issues and most of users are creating threads at wordpress support forum.

I had also faced this problem and fixed in the following way. So Here is the simple solution.

Login to your cPanel and browse ftp folder. Now Open “wp-config.php” file with “Code Editor” and Scroll Down at the bottom of the file. Here you will see this line : require_once(ABSPATH . ‘wp-settings.php’);

Just add: define(‘CONCATENATE_SCRIPTS’, false );  right before the above line. Save the file.

Thats it. Done.

I hope it works for you.