1. Try reconnecting your keyboard, restart your computer and see if that fixes it.
2. Turn off the computer. Unplug the keyboard connect and check for any bent or broken pins.
3. Try updating the device driver. Visit the manufactures web site for the latest driver for your keyboard.
4. While at the manufactures web site. See if there are software patches or updates available for your keyboard. If there are, go ahead and install them as well as the updated driver.
5. If you are using a multi-media type keyboard, be sure to delete the software before installing any new drivers for this type of keyboard. Install the updated driver for the manufactures web site and then re-install the keyboard software. If any software updates or patches are available for your multi-media keyboard, install them at this time. Delete the keyboard software by using Add/Remove Programs. If you receive a prompt asking if you would like to remove all shared files, answer "No to all". Then click OK.