what if i forgot 28 recovery key

If you don't have your 28 character recovery key, there is no way regain access to your account. Apple cannot access your account either in any way.

You were warned about this when setting up that security option:

How to generate a recovery key - Apple Support

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 lose both of these items, you could be locked out

of your account permanently. With that in mind, it's important to keep

your recovery key in a safe place. You might want to give a copy of your

recovery key to a family member, or keep copies in more than one place.

That way you always have your recovery key when you need it.