If you need to restore a User, Course, or Lesson that you have archived (and not permanently deleted), you can do it from the Archive section. 

To restore an item, click the restore (2) icon from the Operations (1) column.

A pop-up message will appear. Confirm (4) your request.

Restored items will now be available again in your system.

Note: To see how to permanently delete items with the trash bin (3) icon, read this article.