Sorry. Should have read closer.
I have seen on some occasions, if someone poorly executes their menu file, it can affect the menu overall preventing entries from other plugins from showing up. I don't have a sure answer for you. I have not experienced any plugin menu related issues as of late. Maybe you could try disabling different plugins and see if it starts working again.
If you are still having issues, there are a number of posts on the forum that mention reseting everything; that might help.