Guided Access

1. Force restart the iPhone / iPad --> Force restart iPhone - Apple Support
2. iPhone restarts> Enter Lock Screen Passcode --> Click-> If you forgot the Lock Screen Passcode for your iPhone, iPad, or iPod touch, or your ...
3. Then go to Settings -> Accessibility -> Guided Access and change the passcode

Guided Access with iPhone, iPad, and iPod touch

1. Go to Settings > Accessibility, then turn OFF Guided Access.
2. Tap Passcode Settings, then tap Set Guided Access Passcode.
3. Enter a passcode, then re-enter it. From here, you can also turn on Face ID or Touch ID as a way to end a Guided Access session.

Use Guided Access with iPhone, iPad, and iPod touch - Apple ...

Guided Access will only work inside of an app. Not in Settings or on Home Screen