If you only see the word Navigator without a picture below it then you’ve collapsed that section. To expand it, again, click the little triangle to the left of the word Navigator.
Or if the entire left panel is gone, then click the little triangle at the left side to expand the left panel.
If something else has occurred please give more details of what you see, now, or post a screenshot.
i'm sorry; the box within the navigator window that we
slide around to move around a magnified photo.
Came back with restart. thank you