My friend forgot her Apple ID password

Forgot Passcode or Password?

Have you forgotten your passcode?, 

(< iOS 15.2) See this Apple article: If you forgot your iPhone passcode

If you forgot your iPhone passcode - Apple Support

(iOS 15.2 and newer) How to reset your iPhone, iPad or iPod touch if you've forgotten your passcode

How to reset your iPhone, iPad or iPod touch if you've forgotten your passcode – Apple Support (UK)

See -> If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

Have you forgotten your password? -> See this Apple article: If you forgot your Apple ID password

If you forgot your Apple ID password - Apple Support

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support