My child forgot his password for his Apple ID
You state this is a child. If you set up the account as part of setting up accounts for younger children through Family Sharing this special method may be available to you:
Family Sharing and Apple ID for your child - https://support.apple.com/HT201084
- "Your email address is the rescue email address for your child’s account, and you can use it with the security questions you provided to reset a forgotten password. You can keep your your child's account more secure with two-factor authentication."
If this is an older child you can go the more usual route for a forgotten password:
Click on this link to read what to do "If you forgot your Apple ID password" --> https://support.apple.com/HT201487
or go directly to this link --> http://iforgot.apple.com/
Also read about "What to do after [or before] you change your Apple ID email address or password" - https://support.apple.com/HT204071
If you still need help:
Contact Apple for help with Apple ID account security "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues." --> https://support.apple.com/HT204169
If you didn't receive your verification or reset email - Apple Support - https://support.apple.com/HT201455