Have you downloaded and installed the correct software, Digital Camera Software 5.1 [Windows]?
Are you certain that you have the proper cable for connecting the camera? Not all of them are alike. Try more than one.
Are you turning on the camera after you have connected the USB cable?
Do you have Windows Media Player installed on your computer?
My Powershot SD-1200 IS was not recognized by windows 10. I was receiving an error message on the camera that said "Comunication Error". After speaking with Lauri at Canon, she found the obscure error message, saying the camera cannot be recognized becaause there were too many photos. I removed several uneeded videos and erased a number of picutres and tried it again and all worked as normal. Thank you Lauri!