Try these checks in order:
- Check basic hardware first
- If it is a USB keyboard, unplug it, wait a moment, and plug it back in.
- Try a different USB port.
- If a USB hub is being used, remove it and connect the keyboard directly.
- Check for cable damage, low battery, or dirt blocking keys.
- If possible, test the keyboard on another PC. If it does not work there either, the keyboard may need replacement.
- Check Windows keyboard settings
- In Windows 10: go to Settings > Ease of Access > Keyboard.
- Make sure Sticky Keys, Filter Keys, and similar keyboard options are turned off if they were enabled unintentionally.
- Check language/input settings
- Go to Start > Settings > Time & language > Region & language.
- Make sure the keyboard input language matches the display language being used.
- Reinstall the keyboard driver
- Open Device Manager.
- Expand Keyboards.
- If a keyboard device shows a warning sign, uninstall it.
- If the device is disabled, enable it.
- If needed, uninstall the keyboard devices and restart Windows so the drivers reinstall automatically.
- If using a Surface Pro Keyboard or Type Cover
- Re-attach the keyboard so all magnets touch the bottom edge of the Surface.
- Press Caps and Fn a few times and check whether the LED lights turn on and off.
- If the LEDs do not turn on, that points to a hardware issue and a service order is recommended.
- Test outside Windows on Surface devices
- Turn off the Surface and wait 10 seconds.
- Press and hold Volume Up, then press and release Power.
- Keep holding Volume Up until the UEFI screen appears.
- Try the arrow keys there.
- If the keyboard works in UEFI but not in Windows, the issue is likely software.
- If the keyboard works in UEFI but not in Windows on Surface
- Use Reset this PC > Keep my files > Cloud download to reinstall Windows while keeping personal files.
- This removes settings changes and apps/drivers that were installed later.
- If only some keys fail or repeat
- Remove dust or debris with compressed air or gently vacuum the top of the keyboard using a dusting brush.
If this is a built-in laptop keyboard and it still does not work after driver reinstall and settings checks, the next likely causes are a hardware fault or a device-specific driver problem from the laptop manufacturer.