Many times when we insert USB drives into the USB port Windows shows up a message that USB is not recognized by Windows 7 as it has malfunctioned. This error can happen if you insert mouse, pen drives, mobile phones or even digital cameras and as a result of this you will not be able to use it. Sometimes even after reinstalling the drivers, you still face this issue.
How to Solve the issue?
Apparently there are many ways to try solving this issue.
STEP 1. Click Start-> Run and type Devmgmt.msc, and this will open up the Device Management. Click to select your computer as the location for the scan. Right click on the computer and click Scan for hardware changes, you can also do this from the actions menu.
Most probably Windows will be able to detect the problem and recognize your USB drive. In case you still face the issue, try step 2.
STEP 2: Click Start-> Run, type Devmgmt.msc, opening the Device Management. Expand Universal Serial Bus controllers and right click on the USB drive which is showing error or not recognized issue.
Select properties from the right click menu and select 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. Now from the the Action menu, click Scan for hardware changes as mentioned in STEP 1.
Windows will again start scanning for changes and it should be able to find out USB device.
STEP 3: If you are still not able to solve the problem, power off the machine, disconnect the USB, pull the battery (in case of laptop) or remove the power connection to PC (in case of desktop), and let it sit for about 10-15 minutes. Restart your PC and it should be able to detect the USB. In this case you are actually restarting the mother board by removing the power and this should solve the issue in most of the cases.