Hi. I'm David, and I'm happy to help you.
Is this a recurring problem or the first time it has happened?
Even if the keyboard itself isn't working, you can usually force your PC to shut down by holding down the power button for a few seconds. Usually, you only need to hold it for 5 seconds to force it to shut down. But I've seen a laptop where you need to hold it for about 15 seconds.
The power button (the same button used to turn on the laptop) is usually separate from the keyboard internally, although it appears to be part of the keyboard.
So, hold the power button until the laptop turns off. Then, turn it back on and see if the system starts up properly.
Let me know the result. Click on the "Reply" button below my reply.
Feel free to ask back any questions.