Moving this discussion to the Photoshop Lightroom forum.
There is a menu bar at the top right of the Lightroom screen that should say "Library Develop" and some other things. If you these are the menus you mean by "File Handling dialog box" then right-click on Develop and place a check mark next to Library. If "File Handling dialog box" means something else, I guess you need to describe it in more detail.
You can always get to the Library from anywhere else in Lightroom by pressing G
Thank for the reply and solution.