Since the laptop keyboard fails but an external keyboard works, the issue is likely with the built-in keyboard hardware or its connection.
Try these checks in order:
- Clean the keyboard.
- Check for dirt or debris stuck under the non-working keys.
- Use compressed air to blow dust out from between the keys.
- Check Windows keyboard accessibility settings.
- In Windows 10: Settings > Ease of Access > Keyboard.
- Turn Sticky Keys and Filter Keys on or off as needed to test whether they are affecting input.
- Confirm the laptop keyboard is the problem.
- Since the external keyboard works, that points to the built-in keyboard rather than general Windows input.
- If needed, test whether the same keys fail consistently and inspect for physical damage.
- Check for hardware failure.
- If keys are cracked, damaged, have fallen off, or continue to repeat/drop input, that indicates hardware failure and the keyboard may need repair or replacement.
- If the problem started after updates or software changes, install Windows updates and check keyboard drivers from the laptop manufacturer.
If the built-in keyboard still does not work after cleaning and checking settings, repair or replacement of the laptop keyboard is the likely next step.