Some keyboard keys do not work. All remaining keys work normally. The laptop works properly with an external USB keyboard attached.
Reinstalling the operating system doesn’t help.
1. Bad connection between the keyboard cable and motherboard.
2. The laptop keyboard failure.
3. The motherboard has a failed keyboard controller.
Possible troubleshooting steps and repair solution:
If some of the keys on your laptop keyboard stopped working, most likely you have a failed keyboard. Before you replaced the keyboard with a new one try reconnecting the keyboard cable on the motherboard. Reconnecting the cable might help.
If reconnecting the cable didn’t help, replace the keyboard with a new one. Most likely replacing the keyboard will fix your problem.
If not, most likely you have a faulty keyboard controller on the motherboard. This type of failure is not very common but it happens. In this case, you‘ll have to replace the whole motherboard.