Finally found the solution. When I went to my sheets and picked the viewport, under Edit Type in the Type Properties box....REVIT had taken the "Title" and instead of it showing "View Title" it showed "None." Revit had toggled this to "None" by itself in all of my sheets in this particular project in which I have 50 sheets of drawings. All drawings show no sheet titles or scales. Revit had toggled that to "None" by itself. So I have to take each sheet and go into the viewport, then Edit Type, then "Title" and toggled it back to "View Title." I've never had this happen in any Revit project. Strange.....but at least I found the solution.