Click start control panel administrive tools ,computer management ,device manager scroll down universal serial bus controllers you should see a yellow question mark?
right click to reinstall drivers or
if you can see your usb but its not working
ports(com&lpt)right click update driver

click start click on my computer you should see your pen drive
right click then select format
another way is to control panel administrive tools,computer management disk management right click on your drive select format

hope this helps