If you purchased your domain from a registrar other than Turbify, you must contact that registrar to make any changes to your contact information. If you remember the company to which you paid your original domain registration fee, contact that organization directly.
If you've forgotten your registrar, you can look up your domain in the public WHOIS database with a WHOIS search tool. Your domain record will include the name of your registrar.
To search the WHOIS, visit Whois.com or Tucows Domains. On the search page, enter your domain name and review the results to find the name of your registrar.