MP3 players connect to PCs through the USB port. USB devices are designed to transfer data quickly and recognise the device within seconds. Sometimes this does not work, and plugging in your device will result in the following message: "Unrecognized device has been found" or "USB Device Not Recognized." There are a few different solutions that will usually resolve the errors, assuming the media player isn't broken.
Remove the MP3 player, wait at least 10 seconds and plug it back in. Do this multiple times. It may connect after a couple tries. If not, continue by opening the device manager.
Open the Start menu search box and type "Device Manager." Chose it from the list of available options.
Locate the device by searching for a yellow exclamation mark. If you do not see it, click to expand "Universal Serial Bus Controllers."
Choose the player from the list and right-click it.
Click "Uninstall." Click "OK" to restart when prompted. If there is no change, try again, this time placing a check by "Delete the driver software for this device." This option might require you to reinstall the drivers, so don't try this unless you have the disc handy.
Plug in the media player after the restart. You should see a message stating the device is connected and ready to use. If this fails, find the website for the manufacturer of the MP3 player to see if there is a firmware or driver update. Install the update according to the instructions.
Do not connect the device through a USB hub or adaptor. Often they don't provide enough electricity to power on the device. Sometimes resuming from standby or hibernation will disable the USB ports. Restart the computer to reenable them.