How do I restore missing Finder folders on MacBook Air?

Last night for no apparent reason my finder folders disappeared. I used to see folders for Desktop and iCloud Drive. Now I see the following: Air Drop, Recents, Downloads, On My Mac as the first folders on the top left. I don't ever remember Air Drop, but missing are the Desktop, iCloud, and Documents folder. What do I have to do to get them back? Thank you.

[Re-Titled by Moderator]