The short answer
Test whether the keyboard works before Windows loads, by entering the BIOS at startup. If it works there, the problem is software and a driver reinstall usually fixes it. If it does not, the keyboard, its cable or the board has failed, and an external keyboard confirms which.
A keyboard that has stopped working entirely is either not being read by the operating system or not sending anything. Those are very different problems, and one test at startup separates them before you spend time on anything else.
Step 1: does it work outside Windows?
Restart and enter the BIOS
Usually by tapping F2, F10, Delete or Escape immediately at power-on. The key differs by manufacturer and is often shown briefly on screen.
Try the arrow keys and typing in the BIOS
If the keyboard navigates there, the hardware works and the problem is in Windows.
If nothing works in the BIOS
The keyboard, its ribbon cable or the motherboard connection has failed, and no software fix will help.
Connect an external keyboard
So you can work while diagnosing, and to confirm the computer itself is fine.
Step 2: software causes
- Reinstall the keyboard driver. In Device Manager, under Keyboards, uninstall the device and restart. Windows reinstalls it.
- Check Filter Keys. This accessibility feature ignores brief or repeated keystrokes and, when enabled by accident, makes a keyboard appear dead or wildly unreliable. It can be switched on by holding the right shift key for eight seconds, which happens more often than you would think.
- Check Sticky Keys and Toggle Keys in the same accessibility section.
- Check the keyboard layout, since a keyboard producing the wrong characters is a layout problem rather than a fault.
- Update or roll back after a Windows update, which can replace a working driver with a generic one.
- Boot into safe mode, where a working keyboard points at software and a dead one points at hardware.
Filter Keys is the single most overlooked cause in this category. The symptom is keys that need to be held down to register, or that ignore rapid typing entirely, which people describe as a failing keyboard. Turning it off in accessibility settings takes ten seconds.
Step 3: a few keys rather than all
If some keys work and others do not, the cause is different:
- Debris under the keys, particularly in a row or a cluster. Compressed air at an angle, with the laptop tilted, lifts a surprising amount.
- A spilled liquid, which corrodes the membrane and typically takes out a contiguous area.
- A stuck key holding a modifier down, which makes everything else behave strangely. Look for a key that feels different, and test with an on-screen keyboard to see whether a modifier shows as held.
- A damaged ribbon cable, which often affects a group of keys rather than all of them.
- Number lock, where part of the keyboard produces numbers instead of letters on laptops with an embedded numeric keypad.
Step 4: liquid
If something was spilled, act quickly and accept that the outcome depends largely on what was spilled. Water is survivable; anything sugary or acidic corrodes.
Power off immediately, do not wait for a proper shutdown, unplug and, if the design allows, disconnect the battery. Turn the laptop upside down to drain, and leave it somewhere warm and dry for at least 48 hours before attempting to power it on. Do not use a hairdryer, which drives moisture further in.
Even then, sticky residue under the membrane often remains, and a keyboard replacement is the usual outcome.
A laptop that has had liquid spilled on it should not be charged or powered on until it is thoroughly dry. Most of the permanent damage from spills happens when power is applied to wet circuitry rather than from the liquid itself.
Step 5: the replacement question
Laptop keyboards are consumables. On many models the keyboard is a separate part held by screws and a ribbon cable, and replacement is inexpensive. On others, particularly thin machines, the keyboard is riveted into the top case, which means replacing the entire palm rest assembly and a much larger bill.
Searching your model number with the words keyboard replacement will tell you which category you are in within a minute, and that determines whether repair or an external keyboard is the sensible answer.
For a machine that mostly lives on a desk, an external keyboard is a perfectly reasonable permanent solution and costs a fraction of the repair.
How do I know if it is hardware or software?
Test in the BIOS at startup, before Windows loads. Working there means the hardware is fine and the problem is a driver or a setting.
What is Filter Keys and why does it break my keyboard?
An accessibility feature that ignores brief or repeated keystrokes. Enabled accidentally by holding right shift for eight seconds, it makes a keyboard appear unresponsive. Turn it off in accessibility settings.
Some keys type numbers instead of letters. Why?
Number lock is on and the embedded numeric keypad is active. Pressing the number lock key, often with the function key, restores normal behaviour.
I spilled a drink. What should I do?
Power off immediately without waiting for a shutdown, disconnect power, turn it upside down to drain, and leave it to dry for at least 48 hours before powering on. Do not use a hairdryer.
Is replacing a laptop keyboard expensive?
It depends entirely on the model. Some are a cheap separate part; others are riveted into the top case, which means replacing the whole palm rest. Search your model to find out before deciding.
The order
Test in the BIOS to separate hardware from software. Check Filter Keys and the other accessibility settings, then reinstall the keyboard driver. For partial failures, look for debris, a stuck modifier or number lock. Treat spills as urgent and keep the power off. And find out whether your model’s keyboard is a cheap part or part of the top case before deciding between repair and an external keyboard.
