If your Apple ID is locked or disabled - "If you or someone else enters your password, security questions, or other account information incorrectly too many times, your Apple ID automatically locks to protect your security and you can't sign in to any Apple services. You can unlock your Apple ID after you verify your identity."
https://support.apple.com/HT204106
What to do after [or before] you change your Apple ID [email address] or password - "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." - Or if you're seeing persistent disabled messages or repeated requests for the password to your previous Apple ID.
https://support.apple.com/HT204071
If you cannot resolve it yourself try one of these two contact methods:
"Use this form for assistance with account and billing, code redemption, or purchase questions."
https://www.apple.com/emea/support/itunes/contact.html
Contact Apple for help with Apple ID account security - https://support.apple.com/HT204169