Noob. Need help with broken(?) lens

[dustin746]

Hey everyone, I've had my DSLR for a little while but when it comes to doing anything internal, I'm a complete noob.

I dropped my camera the other day and noticed afterward that the autofocus was not working, the motor hums but the focus doesn't move. I took the lens off and noticed a small black plastic piece came off the back of the lens. I'm assuming it's part of the focus.

Manual focus works fine, autofocus doesn't. Anyway, can anyone tell me how to put it back on, or if it's even possible. It doesn't look broken, but I've tried getting it back in place and I can't get it back on the lens.

Here's some pictures:

Thanks!

 

[Bryston3bsst]

It looks like there are three tabs at the outer edge of that cover. I also see three appropriately placed holes that I bet the tabs snap into.

It really makes no different as that lens needs to go to the manufacturer for repair what with the AF not working. That plastic ring looks like just a cover. Who made it?