carolynvictoria on "[Theme: Hueman] Lost Several Sub Menus Today"

I've been developing a site with the Hueman template which is very good. Today after adding a sub-menu item to a dropdown menu, it hung and following that, 3 major sub menu trees disappeared. In fact, the entire navigation menu was gone. I was able to rel-link the main menu but 3 major sub menus are lost. Can you shed light on why this would happen. This is a fairly large site. Are there limits as to how many submenu items can be listed? Or some other reason why these menus are now gone? It represents many hours of work and last backup will exclude a lot. My versions are all up to date and no virus on the server. Is there a link table in the database that might relink these missing items if I could update it manually? Any help or pointers would be appreciated. My dev site URL: http://50a.f24.myftpupload.com/ I am using Hueman free template with child theme.
Carolyn Victoria