A domain is the physical address you type in to be directed to your website. Typically, clients who have purchased their domain themselves will know who their domain is registered with and the login information in order to access the DNS (Domain Name System) information. However, if you do not have this information, you can simply go to www.who.is.com, type in your domain name and click "search." From there, you will be able to see with who the domain is registered with.
You will then go to the registrar website (such as godaddy.com, networksolutions.com, etc.) that the domain is purchased with and try and log in with a username and password that you may have on hand. If you cannot remember the password, but can remember the email associated with the account, which also can typically be found on who.is under registar data, then you can click “Forgot Password” and a new password will be sent to the email address in order to log in.
If you cannot remember the email address associated with the account, you will need to directly contact the registrar over the phone to prove you are the account holder. Many times, they provide you with the username and password to log-in, and in this case, you will hand over the means to log in to your Project Manager, who will link the domain to the new site.