I think my iTunes account has been hacked

i just tried to updates my apps in itunes and itunes said my password was wrong, but it wasn't. when i tried to reset the password, it asked me for my birthday. of course, i know my own birthday but it said that was incorrect

this is the warning i got:

The authentication information provided does not match our records. Please verify your personal information and try again.

i tried the e-mail reset and nothing came, so maybe the registered e-mail was also changed. because of that, i can't proceed with resetting my password. there's no way i have my password and birthday wrong.

what can i do about tis?