Here are a few sample messages (please review with the legal team before using):
Example one:
You've requested a page, either by typing the URL directly into the
address bar or by clicking on an out-of-date link/bookmark that is not
available. Please visit the other areas of our web site.
Example Two:
This page cannot be found. The page you are looking for might have been
removed, had its name changed, or is temporarily unavailable.
Example Three:
Our apologies, the page you requested cannot be displayed.