If yes, go to the manufacturer's and download the proper scanner drivers. You may need a client to scan. Personally, I have a Canon Pixma MP340 and in order to scan I needed to download the "Canon MP Navigator" software, you may need somethign similar.
If no, verify the connection. Plug the USB cable into a different port. If you are running Windows XP or newer, it should say something along the lines of "Checking for Drivers" when you connect it. If it connects, but cannot find a driver for it, go the the manufacturer's website and download the proper drivers for your model. If it is NOT connecting at all (you can verify by going Control Panel>Printers OR Devices and Printers (depending on your OS), and ensure that it's there), you either have all the USB ports on your computer broken, a bad cable, or a port where the cable plugs into the printer.