...a new account?
You have some decent options.
Name: Settings -> Accounts and import -> Send mail as -> Edit info on the default.
Address: You can't change an address (other than adding dots and +something), but you can create another account and set up a filter to forward any new messages to your old account (or vice versa), and then in the send mail as section mentioned above you can add & use either address & name combo.
Even if you opt for name change only (as companies usually do), you may wish to register the address in any case.