28 character recovery keu

You don't.

Read the link above:

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

how to get another 28 character recovery key

Have you lost the 28 character recovery key?

Try generating a recovery key again, see Related Article -> How to generate a recovery key

👉 Write down your recovery key and keep it in a safe place.