WTH happened to my computer disc player?

Early this morning, about 6:30, I was awakened by this terrible whirring and racket coming from my computer.

I ran into the computer room and pinpointed the noise specifically to the DVD / Disc player. I started pushing the button to eject. It wouldn’t eject, but the noise did stop.

I was finally able to gently pry the shelf out to see this.

I haven’t even used the disc player in, probably, a week, and it hadn’t been used that morning. It’s just been sitting there, then suddenly,with no warning, all hell broke loose! What could have happened, and why?