If you prefer to use your phone number, you can log-in or register a new account here.
If you like the feel of plastic against your fingertips, go ahead and pick up a new card at your nearest location. If you registered your old card, you can merge this new card with your account in the "manage card" section.
Unfortunately, non-registered cards can not be recovered.
If you would like to deactivate your old card, log into your account and click the "change status" button under manage cards.