I deleted my archived email folder and it deleted ALL my inbox with it. How do I recover it?

Check you trash in your email account. If nothing is there, check in your online email account. Some providers may retain even trashed messages for a few days and may be accessible through a restore function of some kind.

Otherwise, you can restore from a backup.

Some providers have an online mechanism wherein which you go to a mail website, login, and you may be able to recover messages outside of your email program. For example, my previous employers retained Exchange email for a little bit of time following deletion. We could delete messages from trash on out desktop. And, if necessary, login to the online mail to recover some messages for a short time. Not everyone does this.

Let me guess... you use gmail, don't you?

Their implementation of IMAP is horribly non standard.

The "folders", don't exist on their system. Those are just labels that appear as if they were folders in your mail client.

EVERYTHING in your gmail account shows up in the "archive" folder in a mail client. If you delete it from there, it deletes it everywhere.