How to enable USB drives , USB ports and USB Mass storage devices ? 14

This post answers the below questions. If you want answers for these you are in the correct place. Else please leave a comment to editor for more information.

1.How to Enable USB Mass storage devices in XP PC within corporate Networks or Public PCs ?
2.How to enable USB drives ?
3. How to enable USB Flash drives or Portable hard disks or Pen drives?
4. How to install USB flash drives in Windows ?
5. How to ?
6. How to download UsbStor.inf for ?

[ Warning: You can get fired from your company if you are caught doing this or caught stealing information from your company . This information is just for essential usage.]

Now if you are someone looking for enabling USB Mass storage devices in your corporate Network or public PC , You need to have access to your c:\Windows\System32\inf folder  or Your windows driver folder.

You also need USBStor.inf file in the folder or anywhere else in your PC. If you don’t have the file most likely your IS team would have deleted this file.

Download the file USBStor.inf  Download here

You can copy this file to your drivers folder C:\Windows\System32\Inf\ if you want others using PC to install USB mass storage devices or keep in your folders just for you alone.

If you don’t want copy to drivers folder your USB Mass storage devices wont be installed automatically, You will need to go to Device Manager and select device (the device with exclamation) And click update driver and point to the USBStor.inf file.

And you also need to change a registry entry to enable to USB Mass Storage devices – How to enable USB registry entry? 

Change value of the below key to 3 to enable USB Mass Storage device, if it already
3 no need to change this value. If your USB Mass storage device is not working even after installation using driver this will be the culprit, companies set this value to 4 to block the USB Mass storage devices.


When you do this, the USB storage device is detected and works automatically if it is installed already.
To set the Start value, follow these steps:

1. Click Start, and then click Run.

2. In the Open box, type regedit, and then click OK.

3. Locate and then click the following registry key:
4. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\UsbStor

5. In the details pane, double-click Start.

6. In the Value data box, type 3, click Hexadecimal (if it is not already selected), and then
7. click OK.

8. Exit Registry Editor.

But many companies wont keep the drivers under C:\Windows\System32\Inf\ folder
So you might need to go to Folder options in and enable * show hidden files as below

And then do a search for *.inf and find your driver folder. Companies with smart Infrastructure teams do this so users wont copy drivers directly.

  • naive

    I can see USBSTOR.inf file in C:\Windows\inf

    and the registry edit values are also as required to enabling.. still the problem exits..

    The mass storage device get detected and disables automatically in seconds… what cud be the problem.. please help

  • Anil

    While changing the value to 3 in the value box in folder

    I am hitting following error:

    Cannot edit start: error writing value’s new content.

    Please help!!

  • John Nguyen

    I did it. It works for my machine running Windows Embedded and block USB Mass Storage.
    Just change resistry #4 to #3.


  • Rakesh

    I can see USBSTOR.inf file in C:\Windows\inf

    and the registry edit values are also as required to enabling.. and i have also changed the value from 4 to 3 but still the problem exits..

    The mass storage device get detected and disables automatically in seconds… what cud be the problem.. please help

  • Naka

    Is it the samething to doing for windows 7

  • Louis Stanly

    Guys, search for file name ” USBStor.inf ” , Right click on it and select Install.
    If it says no permission. Add your username in security tab and install. It will work.

    • Vasi

      This Works!! THANKS A TON….

  • Prady


    My machine’s usbstor – start hexa decimal value is still being shown as 3, but I am not able to access the storage devices frm my machine, any idea what should be done in addition to modifying it in the start <- USBSTOR <- Services

  • Renn

    i try all of theses but it doesn’t work. when i choose the key there is no details on the pane only i can see is no setting and full logging, what should i do?

  • Download the file USBStor.inf Download here.

    this file is not found plz check it once…

  • vince

    Hi I did it but my usb port is not the one that is blocked, it actually blocks a specific external hard drive and the problem is recent,and I was blocked by symentec

  • aditya

    this method works, but when you connect a usb which has never been connected to the computer, it does appear and works.
    pls help for this

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