The drawing tree can be useful for locating out-of-border views, or erased-from-this-sheet views. Use the Resume View command to find any erased views that do not have an associated sheet.
If all of this does not find your view, one possibility is that the view is question is 'partially deleted'. This is a bug, since fixed, that allowed a workflow where deleting a view but still having the deletion available for Undo (and so the view isn't 'really' deleted yet) had the Undo stack cleared without finalizing the deletion. To test for this, set the hidden config 'fix_draw_partial_del_bug yes' and retrieve the drawing. If there is any partial deletion in your drawing, there will be a dialog explaining what was cleaned up. Details may be found in article CS38939.
