tech...again, I dont know which jurisdiction you are talking about, but have a look at :
http://www.landings.com/
1. Click on DATABASES near the top of the screen.
2. Take a guess which country the aircraft
might now be registered in. Select that country from the menu on the left.
3. Search that countries aircraft registrations using either REGISTRATION MARKING or on MANUFACTURERS SERIAL NUMBER.
Best of luck.