Superdrive immediately rejects CD/DVD

What you can attempt is to clean the drive, go to your local office supply store and ask for a CD/DVD cleaning kit. Clean both the CD and DVD lasers per the directions in the kit you select.

If that does not work then your SuperDrive has likely failed. What most users have done is to get a USB DVD drive, one location that sells multiple options is OWC (www.macsales.com), this is a trusted vendor by many experienced users on these forums that specializes in Macs.

Good luck!

Is this a blank CD, commercial CD, one your burned, or all three?

Do try to use a cleaning disk as rkaufmann87 suggested. It's fixed my older optical drive a couple of times.

Did you try both a CD and a DVD? The reason this is important is that the lasers for each media type are different. If one works, but not the other then you at least know that the disc is loading correctly, it's spinning at the correct speed, and that at least part of the optical pickup unit is working. I too have had some success with the cleaning disc that rkaufmann87 suggested, so give that a try.