Give more details as to how it's "stolen" ... you can't log into it? it disappeared? does it ask for a password you can't provide?
With the recent patch was the feature to have your password emailed to you based on the email address you entered when you logged in after the recent patch ... in the D2 login screen, click on "Account Settings" and you'll get this screen:
Click on "Get New Password" and hope the one who "stole" it wasn't wise enough to change the registered email address too...
