Restoring from an older back-up is (relatively) easy,
if we want to restore the whole forum to that earlier date.
Notice "whole forum": this would mean that everything since that last back-up -- new topics, replies, PMs -- would be lost.
Restoring particular items from an older back-up is difficult, as you need to know exactly how replies, PMs, etc are stored in the database files and usually involves a lot of work, working directly on those files. This can only be done by the system administrator, and on previous such occasions he has already said that it is simply too much work.
Sorry Red Mystic, but you'll have jot down as many names as you can remember, while it's still fresh in your mind, and ask them to resend their PMs to you. Many members don't clear their outbox very often, so they should still have copies of what they've sent you.
regards,
Bob