What Causes Injury To Vertebrae In Upper Back?

Hello, I have, what I assume to be, a severe back injury from when I was 16. It appears that I have injured one of the vertebrae in my upper back. When you take a picture of my back you can see all of my vertebrae except for one, it s almost like it is not even there anymore. I have a picture if you need me to send it to you. I m not really sure what to do.