Can I upload my lost Outlook Express emails back to the server?

I have been using Outlook Express to access my SBC Yahoo home email for years. Suddenly this week all my folders became empty. I found that when I integrated Norton Internet Security’s anti-spam package with my OE, that integration turned off the “leave a copy of messages on server” option — That seems to have caused the server to think I had no old emails in my Inbox, Sent Items, etc.

I do full backups of the PC where I am running OE, so I should (if I can find it) have a locsl copy of all the old emails.

Is there a way to tell OE to upload all those old emails back to the sbcglobal.net server?