Some of my keyboard keys have stopped working
Whether it is one dead key or a whole row, the pattern of which keys failed tells you what broke and whether it is worth fixing.
Which keys failed tells you more than the fact that they failed. A single dead key, a dead row and a dead half of the board each point at a different component, and only one of them is worth fixing yourself.
Start with the pattern
Run the keyboard test and press every key, including the ones you never use. Then look at what stayed grey.
| Pattern | Likely cause | Worth fixing? |
|---|---|---|
| One isolated key | Failed switch or debris | Yes, often trivially |
| Two or three adjacent keys | Debris, or a liquid spill in that area | Usually |
| A full row or column | Controller trace or ribbon cable | Sometimes |
| A contiguous block or half the board | Ribbon cable or controller failure | On a desktop board, rarely |
| Every key intermittently | Cable, port or power problem | Yes, usually free |
| Keys work but produce wrong characters | Not a hardware fault at all | See below |
Rows and columns matter because keyboards are wired as a matrix. Keys are not connected individually, they sit at intersections of row and column traces. A failure that follows a row or column exactly is a break in that trace, not 15 simultaneous switch failures.
The wrong characters case
If a key produces the wrong character rather than nothing, nothing is broken. Your operating system is using a different keyboard layout than the one printed on your keys.
The keyboard test reads physical key positions rather than the characters they produce, so this case is easy to confirm: press the key where Q sits on a US layout, and if the test highlights Q while your text editor types A, you have a US keyboard set to an AZERTY layout. Change it in your operating system’s language settings.
Fixing an isolated dead key
On a mechanical keyboard
- Pull the keycap with a keycap puller or gently with two fingers from opposite corners.
- Blow out the switch with compressed air. Debris is the cause more often than switch failure, particularly on a keyboard that has been near food.
- Test again with the cap off, pressing the switch stem directly.
- Still dead: if your board is hot swappable, pull the switch out with tweezers and put a spare in. If it is soldered, the switch needs desoldering and replacing.
Switches cost well under a dollar each and most people buy them in packs, so the practical cost of this repair is time.
On a membrane keyboard
The contact pad under the key has worn through or the conductive trace has broken. There is no economical repair. Replace the keyboard.
Before concluding the keyboard is broken
Rule out everything upstream first, since these cost nothing to check:
- Try a different USB port, ideally one directly on the motherboard rather than a hub or a monitor.
- Try a different cable if the keyboard has a detachable one. Detachable cables fail far more often than keyboards do.
- Try the keyboard on a different computer. A fault that follows the keyboard is hardware, one that stays with the computer is a driver or port problem.
- On a wireless keyboard, replace the batteries. Low voltage causes dropped and repeated keys well before the keyboard stops working entirely.
- Check whether Filter Keys or Slow Keys is enabled in your accessibility settings. Both suppress keypresses deliberately and are easy to switch on by accident.
The rollover case
If individual keys all work but certain combinations do not register, nothing is faulty. Most membrane keyboards can only report between three and six simultaneous keys, and which combinations fail depends on the matrix wiring rather than the keys themselves.
The rollover peak in the keyboard test tells you your limit. If you need more, that is a reason to buy a keyboard with n-key rollover, not a reason to repair this one.
Common questions
Why does my Fn key never light up in the test?
The Fn key is handled entirely inside your keyboard firmware and never generates an event that reaches a browser or any other application. No software can test it. This is normal and not a fault.
One key works sometimes. Is it dead?
Not yet. Intermittent response usually means debris under the keycap or early switch wear. Press it 20 times and count the misses. On a mechanical keyboard, pulling the keycap and blowing it out with compressed air resolves this more often than not.
Can I fix a dead key on a laptop?
Sometimes. If a single key is dead, the switch mechanism under the keycap can often be reseated or replaced with a part harvested from a donor keyboard. If a whole region is dead, the ribbon cable or controller has failed and the fix is a full keyboard module replacement.
My keyboard stopped working after I spilled something.
Disconnect it immediately and do not power it on. Liquid damage causes corrosion that continues after the liquid dries. A mechanical keyboard can often be saved by full disassembly and cleaning with isopropyl alcohol within a day or two. A membrane keyboard rarely survives.
Does a keyboard test detect ghosting?
Indirectly. Hold down several keys at once and watch the rollover peak. If pressing a fourth key causes one of the first three to drop off, your keyboard cannot report that combination. This is a design limit on most membrane keyboards rather than a fault.