If you think you've been hacked and you're unable to log in with your username and password, please take the following two steps:
Reset your password by requesting an email from the password reset form. Try entering both your username and email address, and be sure to check for the reset email at the address associated with your Twitter account.
If you're able to log in after the password reset, please re-secure your account by following the steps listed here.
If you still can't log in, contact us by submitting a Support request. Please choose "Hacked account" from the list of options. Be sure to use the email address you associated with the hacked Twitter account; we'll then send additional information and instructions to that email address. Include both your username and the date you last had access to your account.
If you've lost access to the actual email account associated with your Twitter account, please see this help page.