Thank you for reporting your missing folder issue. In many cases the folder that appears to be missing may have been moved underneath another folder (i.e. Deleted Items, Junk, etc.). Please check to see whether your missing folder has been moved. To expand the folder tree you will need to click on the arrow to the left of any of the folder names listed and you will see if your folder has been moved. To move it back to its original location click on the folder name and drag the folder to the Inbox.
If you do not see the missing folder we can help you to recover your data but will need you to provide us with the name of the folder you are missing. Please understand that your data is not lost. Once you provide us with the folder name we can restore your missing folder and its contents to your account.
Also, if you need help to learn about the new features, here is a url to a self-help FAQ article with links to more information: https://support.office.com/article/40676ad0-c831-45ac-a023-5be633be798d .