It needs to be installed.
However if there is no Driver Required for any USB Device and it is not working that is a different story. But with your original Post you asked about a Driver for an External HDD that was displaying an Error code of 28 which means that the device in question needed it's Driver Installed.
Most USB Flash Drives Do not require Dedicated Drivers unless they are of the type that compresses Data to make out that they are bigger than they really are. So if it shows a 8 GIG Capacity but in reality only has 6 GIG of Storage Space you need to install the required Driver/Software for that device to compress the Data with that particular Flash Drive.
However generally speaking once you have installed one Driver for a USB Flash Drive that doesn't compress Data that should cover most of the Flash Drives that are available that do not compress Data. You normally [b]Do Not[/b] need to install a Driver per Device for Flash Drives but it may be required for External HDD. and will be required for things like Scanners & Printers.
But if the computer was previously reading Flash Drives and is no longer capable of reading them they it is something you have done attempting to get it to work with the External HDD that you originally asked about. Depending on what you did the repair varies. ;)
Col