Read the document:
Manage Apple ID settings on iPhone - Apple Support
- Make sure you are signed into your account
- Verify payment method(s) and billing address as described in Add a payment method to your Apple ID - Apple Support . Items in red have problems.
- If you're using other Apple IDs with services such as Messages or the App Store, make sure those are signed in too.
Other things to try:
- Check that there isn't an issue with Apple's servers: Apple - Support - System Status
- Try restarting your device.
- Check your software is up to date.
If you still have questions or problems:
To contact Apple, click here --> Choose your country or region - Official Apple Support
Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service by telephone --> Contact Apple for support and service - Apple Support