I lost my recovery key

See -> Two-step verification for Apple ID -> Two-step verification for Apple ID

👉 scroll to & read -> What if I lose my Recovery Key?

You can sign in to your Apple ID account page and create a new Recovery Key using your Apple ID password and one of your trusted devices.

1 Go to appleid.apple.com/uk.

2 Sign in with your password and trusted device.

3 In the Sign-In and Security section, click Recovery Key > Change Recovery Key.

Keep your new Recovery Key in a safe place. Your old Recovery Key won't work any more and you can't use it to reset your password or access your account. If you can't see Recovery Key in the Sign-In and Security section, then you are not using two-step verification. 

FYI: write down your recovery key and keep it in a safe place.

OR click Unlock account, to unlock your Apple ID, you must verify your identity.

👉 Keep in mind -> Never post a screenshot with your personal information, such as Apple ID.

The host will delete your screenshot.

See this article.

How to generate a recovery key - Apple Support

And see “What if I lose my Recovery Key?” here.

Two-step verification for Apple ID - Apple Support