Hello, I'm TV Tech1 and I'll be working with you to identify and help you resolve your problem.
Just to let you know, I have had USB cables fail, and I have had SD cards fail on my camera, so it's a good idea to --
1] Test the computer's connectability first. If you are using a USB cable to transfer, find another device in your home that can connect to the computer with that cable.
My camera and my Tom Tom GPS both use the USB cable, so I'll check the cable with both.
2] Next thing I try is removing the card directly from the camera and insert it into the computer. Does the computer respond and show the card is connected to the computer? If not, do you have other SIMILAR cards in your home?
This is a "divide and conquer" testing of your WHOLE SYSTEM to figure out if the Computer can't read your card or cable, if your card or cable is defective, or your camera is the problem.
While it may sound complicated, the whole point of this test is to use MORE than one similar part -- Two different devices using the SAME cable, Two different connections (cable or memory card to isolate the issue)
I found out that I had a bad SD card. First it failed on my wife's computer, then just this week, that same card failed on my computer. I had several SD cards in my home, one one the camera, one in the Tom Tom, one in my Blu Ray player. Swapped cards and the others worked fine transferring camera files to my computer.
Tested USB connection by simply connecting my Tom Tom and the computer always brought up a BOX asking me if I wanted to open the files, or activate a specific program.
So pull out your arsenal of devices, cables, and memory sticks that your camera uses.
Talk to me about your present connections you are using on your camera.. Let's see if we can find other devices /cards that we can swap and see if it's a computer, cable, memory, or device problem, ok?