This might be the issue because of carbon or short-circuit in the keyboard. Thats why the some keys were not working. If this is due to carbon, then you can open the keyboard and clean it with dry cloth and most probably it will start working again.
To do so, find all the defective keys first from [link|https://keyboardtester.io/|keyboardtester.io|new_window=true] and then plug them out. After that take some alcohol (don't use water) to clean it.
It will help you to fix your keyboard. if this don't work then it might be the issue from motherboard circuit. Then you need to repair it or maybe need to buy a new one.