I bought a used canon

Since this is a used camera, it's possible that the USB port on the camera is not functioning correctly. It is also possible that the USB cable isn't working correctly - try another cable. If that dosn't solve the problem, the least expensive fix is to use a card reader and remove the memory card from the camera and insert it in the card reader in your computer. Then you can use Digital Photo Professional (often called DPP) to transfer the photos from the card to your computer, or you can just drag-n-drop using Windows Explorer or Finder (if you use a Mac). You may already have a memory card reader on your printer - if so you can use that. Or you can buy a card reader at most camera and computer stores - they aren't very expensive, usually less than $20. Just make sure you buy one that works for the type of card you are using in this camera.