I've changed my ID and now i can't connect my itunes !!!

Please read this link and learn "What to do after [or before] you change your Apple ID [email address] or password" --> https://support.apple.com/HT204071 - "After you change your Apple ID email address or password, you might need to update your sign-in information with any Apple services you're using." - You may also wish to turn off "Find My" before changing information and turn it on again afterward.