Computer not detecting USB Flash Drives

I had many old computer hardware and therefore I rebuilt many of the hardware's inside my pc and then upgraded to Windows Vista. After this upgrade whenever i try to connect any usb flash drives it wont get detected. Since, I have a use mouse and keyboard that is working fine on this same system, then I dont know why only the usb drives not working? I have already tried removing and then reinstalling all the USB drivers but it doesnt seem to be working. Can anyone tell me what should I do in this case?

Have you checked whether the usb drive shows up in the Windows Explorer when it is connected to your pc? If not then you can also check if it is shown in the Device Manager or maybe the Disk Management? Did you also try to check if the autoplay pop-up settings in the control panel are enabled or not for any devices that are connected to the computer? You can even try to do a update of your motherboard BIOS. It will definitely solve the case.

I have checked under Windows Explorer and no where it is listed. I have also made the assurity that this usb drive's letter doesnt conflict with any other drives that I have on my computer. It isnt simply getting detected in the pc. And the usb mouse and keyboard are working fine, so I dont think that it is a problem with the USB port itself. Also, I was not able to find any specific BIOS for my motherboard.

Well, if the usb flash drive isnt showing anywhere, whether it is the Windows Explorer or the Device Manager, then I would assume that the usb drive itself might be faulty or damaged and hence it is not getting recognized. Have you tried using the same drive in different computer and checked if it is shown properly? Also you can even try to plug the usb in different usb ports on your computer and see if it can be used. This is simply a case of faulty usb drive I can bet, or perhaps the usb port itself.