It sounds like you are using a POP account. If this is the case once the messages have been removed from the server they cannot be put back. The messages will only exist in your email client (Outlook) unless you were to forward them to yourself but this would cause duplicates in Outlook. In the future if the account is configured to "leave a copy of messages on server" all future emails will remain in your inbox on the server and in Outlook.
See the link below on how to configure this option in Outlook 2007.
http://www.webdesignerexpress.com/ho...rticle-53.html