Hi,
Does your keyboard work while it's inside Windows already? Is it happening only on the lock screen?
Do try these troubleshooting steps that may help.
- Uninstall/reinstall the keyboard driver from Device Manager.
- Once uninstalled just reboot your laptop and it should reinstall automatically after the reboot.
- If these doesn't work try and connect an external keyboard and see if the same problem will persist because if it does it means you'll need to perform a complete factory reset with it.
- If it does happen still after the factory reset you'll need to contact Toshiba support.