iTunes not accepting my Password

Make sure about your ID and password!
If your password is correct and the ID isn't then you obviously can't connect to the iTunes Store.
If you were sure in these things and against it you couldn't or can't sign in, then you have to turn to Apple.
If you got emails from the Apple, which contained informations about your account then look up these emails and maybe you'll find some good information for that. (e.g.: if your ID is not correct you can see that in this or these messages)
If my advice won't help you (I mean checking the ID and password) then turn to Apple for professional help or write in to Discussions > iTunes, maybe people could help you there.

This same thing happened to me. It turned out that my kids had been trying to log into iTunes by guessing my password incorrectly, and Apple had disabled my Apple ID for security. First, I re-set my password by following the email link from Apple. Next, I had to go to my settings and check Apple ID enable to make it work again. Hope this helps!

No this seem to be an "iTunes" issue. As I have a mac.com address/account I have the same login/email and password combination for iChat, iDisk, the Apple Store, Back To My Mac and iTunes. All the above except iTunes accept the password and work. Even when I went into my .Mac account and changed the password iTunes would not accept the new password