Items not appearing on Mac desktop

Well, today I was creating a new folder and it didn't appear on desktop. I tried to add other stuff to desktop and it simply wasn't showing up. When I went to finder and checked the desktop category the folder and the stuff was showing up there under desktop, It just wasn't showing up on the desktop. When I contacted apple support about it, they told me to update my Mac and if it doesn't work I should contact a senior advisor. Now I dont think the update is the issue but I will still do it. If anybody knows whats going on here please help.

[Re-Titled by Moderator]