Did it just start doing this but it worked before? Go into Device Manager-Hardware. Are there any exclamation marks? If there are, delete and restart Windows to try reinstalling the driver.
If that doesn't help, you can try tricking Windows into thinking you have new hardware to find.
Turn off the computer, disconnect the cable and power connector. Turn it back on and let Windows load up. Now, turn off your computer again and hook it back up. Start the computer again and see if Windows finds it this time and installs the driver for it.