Inbox folder of Mail went empty, How do I get the mails back ?

Tom Kramer wrote:

Somehow my 'all inboxes' mailbox in Mail disappeared. How can I get it back?

Yes. Move your mouse to the right side and + to add it back in...

Thank you from me too, same happened to me.

All of my favorites are grayed out in this drop down. I need to add them all back into the favorites along with the all inbox folder. How do I do that if they are all grayed out?