Diablo 3 Our login system has detected a change in your access pattern. In order to protect the account, we require you to verify your identity via a message sent to the e-mail address associated with this account. For more information, please visit [us.battle.net/account/support/password-reset.html]. (Error 42003)?

Answer 1

Go check your email that you signed up with and follow the instructions, not that hard.