I believe this is with regards to the username of your Nokia account. What particular account are you referring to when you say you can't find the username? Are you trying to open the account by using the username in the URL to access directly the account or is the username not appearing as signed in when you access a particular Nokia service like Nokia music or Nokia store? In the device first use, you are being asked if you want to sign in or create a Nokia account on your phone to enjoy the services on the phone. Have you done this already on your phone?