If your domain shows as Registrar Lock this means that there is a problem with the domain and you will need to contact the company that you registered your domain with. Registrar is the term used do describe a company that you can register a domain through. If they have locked your domain you will need to contact them for the specifics on why.

If you registered your domain through Yahoo! you will need to contact the service that it it hosted with (ex. Merchant Solutions, Hosting, Mail, etc.)