I get these messages every month or so, and it is rather depressing. It shows that the sender has not bothered to read even the most basic information on this site. Hard to say exactly, but over 1,200,000. This is up from less than 500,000 a year ago. Domain names do not exist until the first time they are registered.
Domain names are concepts.
In the same way, you have to pay to register trademarks, which are often new words that never existed before. If you just want to change details such as the technical or administrative contact, you can simply fill out a form on the InterNIC site and the change will be made in a few days. This change is free. You can use whois to find out details of a domain name, or to find a domain name based on details about it. I can't find my domain name on the Web.