I'd suggest creating a new question by clicking Ask a question at the top of this page if this method doesn't work:
Right-click Start button and choose Device Manager > expand the Keyboards section > right-click the driver and choose Uninstall driver > proceed to uninstall it. When it's uninstalled, click Action > Scan for hardware changes and it'll install back. If it doesn't, try a restart. If after restart, the keyboard still doesn't work, download the latest drivers for your device from the PC / MOBO manufacturer's official site.