Outlook - Restore the Unread Mail folder (Outlook 200x/201x/365)

Here it is Microsoft official article that instruct you on how to re-enable "unread email" folder in Outlook 200x/201x/365 in case it is no longer available.


Tip: You can also open the New Search Folder dialog box by pressing CTRL+SHIFT+P.

Here they are some screenshot about resolution steps done on Office 365: