Deleted mailbox in OE

I've done a really stupid thing and accidentally deleted an Outlook Express mailbox instead of one email in the mailbox! This was a mailbox I created for filing away emails from a certain category of people.

I have used software in the distant past to retrieve individual emails, but I can find nothing on how to recover a whole mailbox. Is there some special technique that can be employed, or is this something that involves the purchase of special software?

Would a system restore bring back the mailbox and its contents?

I am just about to look at my backup to see if it can be restored.

Thanks.
Diane