private forums not working?

When private forums are enabled, the link goes to an error page with the following info:

We’re sorry, but we can’t find the page that you’re looking for. Perhaps searching will help.

How do I fix this issue? It just happened out of nowhere. Please use as simple terms as possible if you have a solution – I am not familiar with coding verbage (I am an average computer user), but our site owner (who IS) has been MIA for months.

Thank you!