Thank you all for your input on this problem. The camera shop has determined that the problem was in the slot for the SD card and givwn me a reasonable repair cost. My only regret was that I did not open the camera and do the repair myself. I had purchased a used t 2i to keep me going while the repairs were in progress but only managed one photo-shoot before a slight illness interveiened and kept me house-bound for the past week. So now I have a spare camera!😊