Error code on radio

I am getting a "CD ERROR" on my radio when I hit the CD button. I cannot eject the CD casette in the trunk either. It makes noises like it's going to spit it out but then it just stops working. Help! What is wrong and how do I fix it?

I am getting a "CD ERROR" on my radio when I hit the CD button. I cannot eject the CD casette in the trunk either. It makes noises like it's going to spit it out but then it just stops working. Help! What is wrong and how do I fix it?
=====
I have a '96 328 and the radio recently started giving the same "CD error" message when I try to play a CD. At the same time, the volume adjustment vanished, i.e., I can turn the knob just fine, but it no longer controls the volume up or down.

My casette player still works fine.

Any suggestions on how to regain full utility of the otherwise wonderful stero system?