If your computer does not recognize the USB device.In this you can get an idea on what to do when your computer displays an error message like "USB device not recognized" when you plug in a usb device in a usb port.


first try method 1 to work around this issue.

Method 1: Initiate recognition of the USB device by using Device Manager

To initiate recognition of the USB device by using Device Manager, follow these steps:
Click Start, click Run, type Devmgmt.msc, and then click OK. The Device Manager window opens.
Click to select your computer as the location for the scan.
On the Action menu, click Scan for hardware changes.

Windows  recognizes the new device.
Close the Device Manager window.
If this method resolves the issue, you are finished.

If this method does not resolve the issue, go to method 2.

Method 2: Disable power management of the USB hub
Note If you perform the following procedure, you may also reduce the battery life on a portable computer.

Use this method if method 1 does not work. To disable power management of the USB hub, follow these steps:
Click Start, click Run, type Devmgmt.msc, and then click OK. The Device Manager window opens.
Expand Universal Serial Bus controllers.
Right-click a USB Root Hub in the list, and then click Properties. The USB Root Hub Properties dialog box is displayed.
Click the Power Management tab.
Click to clear the Allow the computer to turn off this device to save power check box, and then click OK.
Repeat steps 3 through 6 for each USB Root Hub in the list.
On the Action menu, click Scan for hardware changes.

Windows recognizes the new device.
Close the Device Manager window.
If this method does not resolve the issue, go to method 3.

Method 3: Restart the computer
To initiate recognition of the USB device, first unplug the USB device and restart the computer. Then, wait five to ten seconds before you plug the USB device into the computer or hub. Windows  recognizes the new device.
(if still you have problem dont try to solve it on your own but contact your manufacturer)

(get more tricks based on usb)