Disable USB/Flash Drives in Window 7

To disable the access to USB port, in windows XP, Vista and Windows 7: 

1. Click Start, and then click Run. ( or press window + R)

2. Type regedit  and then click OK.

3. Navigate to the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor

4. In the right pane, double-click Start.

5. In the Value data box, change its value to 4, which was 3 and then click OK.



Now To re-enable disabled port:
1. Click Start, and then click Run.

2. Type regedit, and then click OK.

3. Navigate to the following registry key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor


4.  In the right pane, double-click Start.

5.  In the Value data box, change its value to 3, which you changed to 4
to disable the USB drive and then click OK.

6.  Quit Registry Editor.

Now whenever a user will attach a USB storage device which is already
installed in system, Windows will not detect it and it‟ll not be shown in My
Computer. However, disabling USB ports totally also disables the ability for
Windows to use USB based keyboard, mouse, webcam, printer, scanner and
etc., which are common devices for a computer nowadays and essential
ones as well.