It is a violation of Upwork terms to create another account. You could have reactivated your old account and updated any outdated information. Now that you have already committed a mistake and your account is suspended, email Upwork support through firstname.lastname@example.org or fill out the appeal application form. Also, try reaching them on Twitter(@Upwork) if the email does not.
Be honest and tell them that you did not know that the old account existed. They may close your old account and reinstate the new one. If your appeal is rejected, then consider using the alternatives we have provided above.