After trying to "fix" my CD player by letting the cartridge pop up from its box, then pushing it down again, with the result that I still got the error message "No CD Player" when I selected CD on the control panel, I tried another tack: I let the cartridge pop up, removed it completely, then flipped out the individual CD holders to see if one of the CDs might have become dislodged. Everything looked normal. When I reinserted the cartridge and again selected CD, it played! Isn't technology wonderful? I think that my removing the cartridge and replacing it had the same effect as hitting the TV used to have...things got better.
Thanks for your suggestions!