How do I return my desktop folder to its original location and functionality?

I was recently trying to convert my desktop into my dropbox folder, and I did so with these two commands in terminal

mv desktop desktop.bak

ln -s /Users/username/Dropbox/ ./Desktop (I replaced 'username' with my username)

Unfortunately, this change was not helpful, as it synced all the items on my desktop to dropbox, which cluttered by dropbox. Every time that I tried to delete an item from dropbox, it disappeared from my desktop as well. To 'solve' this issue, I tried reverting my desktop back with this command

ln -s /Users/username/desktop.bak/ ./Desktop

This allowed me to store my desktop items in a folder called desktop.bak, and then I could unsync my desktop from dropbox

But then I input... ln -s /Users/username/desktop/ ./Desktop ...after creating a new desktop folder in this location.

Now, my desktop is completely empty except for my Macintosh HD, and I can't move any objects over to the desktop. The greyed out transparent icon that usually indicates that you are moving a folder or file now displays a grey circle with a line through it in the bottom right corner. I can no longer use my desktop.

How do I fix this, and revert my desktop back to the way it was when I first got my macbook air???