I am an Admin user on v5.4.2.2. I was unable to "Add Page" to a page on the nav bar. It said "Access Denied". I tried to change the permissions and changed the page from "Manual" to "Page Type Defaults in Dashboard"

Now, the page on the nav bar and sub pages are hidden from view, both from the user view and the sitemap. I do not have a way to change back the Permissions. I doubt the page is deleted.

More important problem: When users log on they get dropped onto the missing page so now users cannot access the website.

I have a call out to my hosting provider, but thought I'd see if there was something I could do on my side.