Hi,
If both built in and external keyboard are not working the problem may lie in the operating system of your laptop. But do try these steps before you do a complete factory reset.
- Check keyboard language settings.
- Open Control Panel and look for Region and Language.
- Check all tabs if they are all set to United States.
- If that doesn't work, try pressing those following keys which are not working using your onscreen keyboard (Ease of Access look for Onscreen keyboard)
- Connect an external keyboard and see if the same problem will persist because if does you may need to consider on doing a complete Factory Reset cause it's a problem with your operating system.