So as it seems to be a common problem with the 6 CD changer, mine as well, would not let me play any CDs. I used the DIY ( http://www.audiworld.com/tech/elec4.shtml ) but still doesnt work; I used a credit card, i dont know if thats too big or not but it didnt do the job. I took a flashlight and looked all around and couldnt see any CD's or parts or any. Car is a 98.5 A4QM if that matters

 

Did you follow this step?

What to do if the magazine does not manually eject freely. Again, don't panic. Remove the CD changer completely from the car, and unscrew the CD mounting bracket from the changer. It is now possible to remove all of the screws on the external housing in order to lift off the black sheet metal housing of the changer. You should immediately see your problem. In my case, I had a CD which was stuck halfway out of the magazine. My CD changer tried to stuff two CDs into the same slot. Using a pair of needle nose pliers, I carefully removed the trapped CD, and placed it into an empty CD slot. Then the magazine manually ejected easily. I then placed the black sheetmetal cover back onto the CD changer, plugged the changer back into my car, turned on the radio, and then followed the rest of the instructions on CD Magazine Eject Manual Override Card. Don't forget that you have to reinsert and EMPTY magazine back into the CD changer.