We have a project in Revit 2009 that was missing most of the gridlines and dimensions in all views (sounds like they were deleted right?) So I tried changing the only gridline left from 10 to 9 (to see if they were infact deleted) and Revit told me that the gridline already existed. So, I thought that maybe the gridline was just out of the scope of the view so I wrote down the element id number in the warning dialog and went to Tools... Element Ids... Select by ID... input the number and clicked on Show. The elements and their associated dimensions magically reappeared in all the views. I'm thinking this is a rare bug (or corrupted file) but I thought I'd shared the solution with AUGI.
Also, when auditing doesn't fix bugs, upgrading to the next revit release can sometimes fix buggy behavior.
These things are worth a try the next time a problem vexes you.
What bizarre solutions have you found in exploring Revit?