Mark has a teenage daughter who has a Windows 8 laptop she bought two years ago. They upgraded to WIndows 10, and now they're having issues with the laptop's keyboard and trackpad. They tried reinstalling the OS, but that didn't work. It does work with an external keyboard. Leo says that indicates a hardware failure, not the result of upgrading to Windows. Leo says that Mark can look in the Device Manager and see if there's any red X's by the trackpad and keyboard. It could just be a bad driver, but then again, they reinstalled the OS and the problem persists. So it has to be hardware.
Since it's out of warranty, she should still try and see how much it would cost to repair. It may be an easy fix. Google the problem. If it's an easy fix, she may be able to repair it herself. But that can be tricky. If it worked in Windows 8, she could try downgrading to see if it works again. If it does, then it could very well be the driver that Microsoft replaced it with. She should check the manufacturer for Windows 10 drivers and try reinstalling them.