They were not in the Trash folder and I checked the All Mail folder and they weren't there either. But they are in the All Mail folder now, so I don't know what happened.
Here is some information for you from a google forum, since you didn't have the correct information.
"Gmail doesn't have folders. All your messages are saved in All Mail. Everything else (Inbox, Sent Mail, Starred, labels, etc) are just "views" into a sub-set of the messages in All Mail. And since there's only one copy of any message, if you delete it from any label, you're deleting the only copy, so it's gone from all of them. If you delete a label you remove that "view", but the messages are still in All Mail.So you can't undo deleting labels, but the messages would not be deleted and should be safely saved in All Mail. You can go to Settings->Labels to re-create your label. But there's no easy way to get your messages labeled again. You'll need to use searches or manually go through the messages and re-apply the labels."
I am NOT satisfied with the answer. As I stated in my question I wanted to know how to "recover deleted FOLDERS" in my gmail account. I deleted the folders, not the emails. There was no bug.
Again, I am NOT satisfied. You did NOT answer my question correctly. If you didn't understand the question, you should have let me know.