If you are like me and upgraded to WordPress 3.5 and find that almost all of the JavaScript is now not working, this maybe why. When you log back in and try to do something like, add a post, you realize that none of the menu bars and plugins have loaded.
The first thing you can try is to enable Script Debug in the wp-config file. This solved the issue for me, but I don’t like a debug flag fixing errors so I dug a little deeper and found the following in the WordPress 3.5 Master Problem Page.
One solution courtesy of WordPress Support Docs: You probably have added Perishable Press’ 5G blacklist to your HTACCESS file. They probably changed the way they do rewrites in this version of WordPress and the HTACCESS file blocks other parts of WordPress from seeing critical files. If you look at JavaScript errors, you get file not found errors. Follow the link below and search for “5G Blacklist” on the page it will take you to the updated code from WordPress.
WordPress Support: http://wordpress.org/support/topic/troubleshooting-wordpress-35-master-list