usb flash drive not recognized

I have a sandisk cruzer 8gb flash drive, and 3 computers. the flash will work on 2 of the computers but not the 1 any ideas why. thank you

PS, the 1 computer will reconqize other usb devices

any ideas why

Oxidized USB 3.0 contacts in the USB port can cause this.  A brief clean up with emory paper should work.

I will try that, but the port on just the 1 computer does detect other usb devices just not the sandisk.


  1. Open Run (Win+R)
  2. Type “compmgmt.msc” , click Ok
  3. In left side click Disk Management , the Disk management window will open.
  4. In right side at the bottom you will get this option “Universal Serial Bus Controllers”. Expand this by click on ‘+’ button.
  5. You will see all the list of USB controllers… you will find a “Unknown Device”
  6. Right click on Unknown Device and click Uninstall.
  7. Restart your system. Now connect USB, window will automatically install the drivers.
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Thank you for your reply. I do not have the option “Universal Serial Bus Controllers”. In the Disk management window.

I also have the similar problem after upgrading from Windows 7 to Windows 10. I tried different USB ports on my laptop and still no luck.

Sloved my problem by buying a new Front USB Audio I/O Input Output Control Panel Board Card. .

Mine was fine but no drive letter was assigned.  I just had to assign the letter in disk manangment and all worked again.

I had the same problem and it just turned out to be a drive letter conflict

Windows is notorious for assigning the same drive letter to different products.

Rony_Kurana has the correct solution that solved my issue. He just meant to type Device Manager instead of Disk Management.

No “Unknown Device” found.