I think you will need to provide additional information. Are you in the Model tab and nothing works? Are you in a layout working through a viewport, etc?
So you are double clicking over the viewport and it doesn't make that viewport active?
You can't see the border of the viewport?
You are in the viewport but you can't zoom in and out?
More details please, otherwise it is very hard to help.
I'm in layouts the model viewport feature on the ribbon is not allowing me to select any of its factions so opening a viewport to put in my title block is not possible. Double clicking it dosn't change anything it is still non responding
Move to the Layout Tab and not the View Tab on the Ribbon.
I have no idea. The Ribbon can be customized however you want it, get used to where it is now or move it back.