Widgets admin page layout change

Hi

Have no idea what has happened. Within an hour of working on my site and having edited a couple of widgets in admin, I returned to the widgets admin section and have the following layout appearing. No idea what has changed and no idea how to get it back to its default layout as we all know it to be.

Any help with this would be greatly appreciated.

Link to screenshot… http://solidsurfacestudio.co.za/wp-content/uploads/2016/02/screenshot-widgets.jpg