Not sure I understand what your problem is. Let me attempt to adress the issues you seem to be having:
Can't play audio CD:
What are you trying to play it with? Can you see any CD you put into it (data, ect)? Make sure that in my computer, you can right click the CD drive, hit open, that you actually see files on the disk.
Can't see external HD:
go to Start -> Run ->type compmgmt.msc -> Go to storage -> Disk managment > Find what looks to be your external HD in the list of **** devices down on the bottom, and to the right of it should be a white box that represents your partition. Right click it and hit "change Drive letter " There should be nothign in the box that coems up (if there is, look at the letter and open up my computer and go to that letter in the adress bar (View -> toolbars -> Adress bar if it is not up) and you should see your files. If the is nothign in that box (the one from computer management), then hit add and assign a letter to your drive. If should then show up in my computer.