I would contact the reseller that you purchased the software from and request the serial number and product key. But if you recently purchased 2004 I question if this is a legitimate reseller? 2004 is no longer available and shouldn't be sold through a registered Autodesk reseller. If you purchased this from an individual from say eBay, this is not permitted, Autodesk software cannot be re-sold
Dwayne Poot Support Specialist Product Support Autodesk, Inc.