Menu disappearance

The menu tree of the website currently has 43 pages. When I added the 43rd, I did something that I didn’t do with any of the others: I changed the title of the page after adding it to the tree. After I did this, the menu disappeared completely from the Website although it’s still in the backend. I tried changing the name back, removing and re-adding the page, creating a new tree… none of it worked. Help!

The page I need help with: [log in to see the link]