First, the error your receiving on your search results is a hidden module which you will only see while logged in as host or admin.  No concerns there.

Have you checked your recycle bin in the admin control panel?

Second, you can identify the TabID of the "missing" page by running a simple query. 
Go to your Host -> SQL  and execute a simple query like the one below.
Select TabID from Tabs where TabName = 'PAGENAME'   or 
Select TabID,PortalID,IsVisible,DisableLink,IsDeleted from Tabs where TabName = 'PAGENAME'

You want to pay particular attention to the IsVisible, DisableLink, IsDeleted columns.   All of those properties can restrict your view of the page in question.