If your Black Studio TinyMCE widget seems to have disappeared after upgrading to WordPress 3.9 you’re not alone.
Many users are looking for the missing widget after the most recent upgrade.
According to the plugin page, the plugin lists that it is compatible up to WordPress 3.9 ( as of April 2014 ) – however you may still be having a hard time finding the editor on the widgets page ( `widgets.php` )
The issues is that the plugin has had some name / title changes. While still called `Black Studio TinyMCE plugin` the name of the widget is just called “Visual Editor”