First look in the device manager and see if it is recognized and working.
What do you mean does not work? Have you tried what already works in that port? Have you re-booted the system with something plugged in to see if it recognizes the new hardware (such as your camera).
Lastly if by chance it is a separate device then look inside the case and make sure it is connected to the motherboard.
If all else fails you can get a cheap USB hub ($20 or less) and run multiple things off your working port.
I HAVE 2 USB PORTS AT THE BACK OF MY PC.
1 WORKS AS I USE IT FOR BROADBAND.THE OTHER ONE
DOES NOT.I WOULD LIKE TO USE THE SPARE ONE FOR
MY COMPUTER IS QUITE OLD AND THE OPERATING SYSTEM
IS WINDOWS ME