Recovery key

From: How to generate a recovery key - Apple Support

If you forget your Apple ID password and do not know your recovery key, you can try to regain access using your trusted device protected by a passcode.

Unfortunately you do not provide specifics as to the problem you are having. If Apple's procedure for resetting your password using a recovery key isn't working, I suggest you contact them using the resources in this document: Contact Apple for help with Apple ID account security - Apple Support

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

BTW:

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

What happens when you use the same Apple ID & Password that you use to sign in here?

See -> Sign in with your Apple ID -> Sign in with your Apple ID - Apple Support