Don't feel overwhelemed, we can fix this.
Get a trashcan ready on the side.
Put all your pencils/pens/highlighters/sharpies into a container like this.
Throw away all used posits, papers, clothes tags and anything you don't need.
Fill up a little desk light organizer with pens, staplers, etc. I got mine at target.
Get some brand new colorful postits to motivate you to work better.
Flowers (fresh or fake) always cheer up a desk.
Here you go, an organized desk! :)