Can't insert discs

Help. I can't insert discs in the superdrive. When I try to insert a disc it goes in to the half. First i thought there was a disc inside but there wasn't anything on the desktop. Then I hit the eject button, there was a sound like ejecting a disc and then...... nothing. I still can't insert it.

Restart the iMac and see if a disk appears on the desktop. If not try turning it on its side (disk slot down) and press eject to see if anything is stuck in there

Nothing appeared. I try turning it down but there was nothing stuck in it. Maybe the mechanism is broken. I used it a couple of day ago and everything was fine.