How2recover outlook2003 emails(no bckup)

I formatted and reinstalled my computer and after puting windows xp on I installed outlook 2003 but now I lost all my old emails and I didnt backup my previous outlook also I cant use system restore as it was a computer format.

How can I get this back ?

I desperately need this emails back thus I installed a nice app that can help me get back all my old program files and music etc but I stil cant get my old mails back.

Any ideas?