The information below is mostly based on Apple's support article: Set up a recovery key for your Apple Account - Apple Support Each section outlines different situations and some strategies that may involve recovery keys. If you are not familiar with trusted devices and numbers, see this support article —> Two-factor authentication for Apple Account - Apple Support
If you still have access to your Apple ID and password but have lost your recovery key:
You can “update” your recovery key from Settings or System Preferences on a trusted device. Refer to the steps in Set up a recovery key for your Apple Account - Apple Support about how to do this on different types of equipment (Apple equipment only).]
- If you have forgotten your Apple ID password, have lost your recovery key, but still have access to a trusted device.
This does not involve using a recovery key. Refer to this support article: https://support.apple.com102656
- If you have a forgotten password and you do not have access to a trusted device:
“you need to provide your recovery key and a verification code sent to your trusted phone number.”
[Older wording —> you can use your recovery key, a trusted phone number, and an Apple device to reset your password.”]
- ”If you use Advanced Data Protection [for iCloud] and set up both a recovery key and a recovery contact, you can use either your recovery key or recovery contact to regain access to your account”
- If you have lost your recovery key and have lost access to both your account and trusted items:
A recovery key is designed as an alternative to Account Recovery ( How to use account recovery when you can’t reset your Apple Account password - Apple Support ) which is where Apple helps you regain access to your account. However, "When you set up a recovery key, you turn off Apple’s standard account recovery process." You can try to contact Apple (see: Contact Apple Support - Apple Support ), but to me the previous statement implies that setting up a recovery key excludes Apple from being able to do anything. Using a recovery key is more secure, but it means that you’re responsible for maintaining access to your trusted devices and your recovery key. “If you don't know your account password and have lost or otherwise don't have a trusted device, you need your recovery key to regain access to your Apple Account. If you can't provide your recovery key, you’ll be locked out of your account permanently.”