W7 First, please disconnect all USB devices and then perform the following steps:

Click "Start" button, type "devmgmt.msc" (without quotation marks) in the "Search" bar and press "Enter". Click "Continue" if necessary.

In Device Manager, double click to expand "Universal Serial Bus controllers", right click on the Host Controller, click "Uninstall" and click "OK".

Repeat the step 2 to uninstall all items under "Universal Serial Bus controllers".


Then, restart your computer and Windows 7 will reinstall all USB controllers automatically. for xp or earlier click start right click on computer select properties device manager scroll down universal serial bus controllers you could see a yellow question / exclamation mark? ! or a red X you will need to update/reinstall drivers right click to reinstall drivers if you can see your usb drive but its not working ports (com&lpt) right click update driver if this fails to fix the problem Check the USB leads that attach to the motherboard usually red white green black make sure they are securely seated and have no dust build up on them dust will cause static and a lot of unforeseen problems to a computer and its parts
Hope it helps.