If you wish, you can reactivate your account simply by posting a reactivation request; see
viewtopic.php?f=11&t=4360 .
Provided you have no other active accounts in the game (which I presume is the case here), you're also very welcome to register a new account. You can register with the same email as before, although if you are registering in the same nation as before, you will need to register with a different username. As I understand it, a username can only be used once in each nation.