generally windows will auto-install generic drivers that will recognize them right away. Often, the memory sticks themselves will come with specific drivers loaded directly on them, which you can simply open the file and it will install them as long as you haven't deleted these files already. Otherwise go to manufacturer site for them. Also, if these drives are formatted without an active partition on them at all, they will not appear in your drive manager whatsoever. You will have to open the windows partition manager, navigate to the thumb drive, and change the active space to a new partition. Format it to NTFS and you're set. Rarely do I ever see this, but I have run across it on cheap promotional giveaway thumb drives given to me by companies trying to advertise their product portfolio. They thought it was loaded with their catalogs...but instead it was unformatted empty space. lol!
what brand of thumb drive is it? also go into the device manager, try uninstalling the driver for your USB ports aswell. once you re-enable it...it will re-install new drivers for your USB interface, and this could also help the issue.