And three hours on the phone with Apple Support - my senior tech never called back so I got a new one. Very nice chap and after much sussing out the CD drive we now know the issue - the USB ports on the computer are putting out power, which is why my speakers work and why I can charge the keyboard and trackpad - but they're not outputting data or anything else, hence nothing shows up on the computer - not it, not the iPhone, not a flash drive. This all happened a week ago, which is just weird, as everything was working up until that point. I either have to try and have that fixed, which I don't have the time or energy or money to do, so no uploading anything into Music, and no setting up a back-up drive to do back-ups. There's only one other workaround that we don't know will work, and that's the Thunderbolt 2 ports, which I've never used. Of course, they don't really do that anymore - it's Thunderbolt 3 now or something - but I found one adapter on Amazon that we could try - it would hook up to the Thunderbolt port and then you'd put the USB stuff into THAT. Maddening.