Mail list as in your Contacts? Anything happen before this to make them disappear? Contacts are stored in the same place as your mail messages, in a .pst file on the computer. If you deleted Contacts and there is no backup of the file, you can try to do a system restore to a date before they disappeared.
Contact may be in a .pab file if you use an Address Book instead of the Contacts in Outlook. Your ISP may have the contacts also on the server, try accessing your account through their email web portal.