Keyboard keys not working? Stuck, dead or misread
A key that repeats or stays down is usually stuck, a key that does nothing is dead, and a key that types the wrong character is usually a layout setting. Test with the keyboard test or a plain text editor first, then work through the causes below in order. Most keyboard faults are fixed by a setting or a clean, not by a repair.
Keyboard testSome keys don’t respond — free, runs in your browserOpen →Stuck, dead or misread
| Symptom | Usual cause | What to try |
|---|---|---|
| Key stays down or repeats | Debris under the key, a worn switch, or a sticky-key setting | Check accessibility settings, then clean |
| Key does nothing in any app | Dead switch, loose connection or broken trace | Try another port or keyboard, then repair or replace |
| Wrong character appears | Layout set to another language | Check the input source list |
| Keys fail only when several are held | Rollover or ghosting limit | Press fewer keys at once, or use a different keyboard |
Ghosting and rollover
A keyboard does not give every key its own wire. Keys sit in a grid, and the controller finds a press where a row and a column meet. When three keys sit at three corners of a rectangle in that grid, a keyboard without protection can read a phantom press at the fourth corner. That is ghosting. Better keyboards add diodes to prevent it.
Key rollover is how many simultaneous presses a keyboard reports correctly. The basic USB keyboard mode used at startup reports up to six ordinary keys at once, plus the modifiers. Some keyboards advertise full N-key rollover, which reports every key you press together. If a key fails only when you hold several others, you are likely seeing a rollover limit, not a broken key.
Start by testing. Open a text editor, press each key slowly, and look at what appears. Then use the keyboard test to see each press registered. A key that works in the test but not in one app points to that app or a shortcut conflict. A key that works nowhere points to hardware or a driver.
Fn lock and layouts
On many laptops, the top row switches between the standard F1 to F12 functions and media or device functions. The Fn key is a modifier that switches between the two. Some keyboards have a Fn Lock key, or use Fn with Esc, to change the default behaviour. If F5 seems to do something else, try holding Fn, or change the Fn lock state. On a Mac, look for "Use F1, F2, etc. keys as standard function keys" in the Keyboard settings.
A layout tells the operating system which character each key produces. If letters sit in unfamiliar places, or a symbol you need is missing, the layout may belong to another language. Check your list of input sources in the keyboard settings. Keep the layouts you use, and remove the rest, so you do not switch by accident.
Developers should know the difference between two browser values. event.code names the physical key position, such as KeyQ. event.key gives the character the layout produces. On a French AZERTY layout, the key labelled A sits where QWERTY has Q, so its event.code is KeyQ while its event.key is a. A game that uses event.code for WASD keeps the same physical keys on any layout. One that uses event.key follows the letters. Neither is wrong, but know which one you are testing.
Cleaning, and when to stop
Power off or unplug first. Turn the keyboard upside down and tap it to loosen crumbs, then use short bursts of compressed air between the keys. Wipe the surfaces with a barely damp cloth, and never spray liquid onto the keys or let it reach vents and ports. A removable keycap can be lifted with a keycap puller, so note where each one goes. Many laptop keyboards are attached to the chassis, so do not pry at them. A key that springs back slowly often has crumbs in its mechanism, and a careful clean can help.
If a key fails in every app, on every port, after a clean and a layout check, it is probably hardware. An external keyboard is usually cheap to replace. A laptop keyboard may be a repair job, so check the warranty first, and do not open the machine unless you know how to reseat its connector. For the same step-by-step approach on another device, see why a webcam is not working.
Accessibility settings that look like faults
Two accessibility features often cause confusion.
- Sticky Keys makes Shift, Ctrl, Alt and similar keys stay on after one press, so pressing Shift twice in a row can look like a stuck key. On Windows, pressing Shift five times turns Sticky Keys on or off.
- Filter Keys ignores brief or repeated presses. A light tap can seem to do nothing, and a key held a little too long may register as a repeat.
On Windows, both are under Settings → Accessibility → Keyboard. Many people use them on purpose, so turn them off only if you do not need them.
Quick answers
Why do keys stop responding when I press three at once?
That is a rollover or ghosting limit of the keyboard, not necessarily a fault. Try fewer simultaneous keys, or a keyboard with better rollover.
Why do my function keys control volume and brightness?
The top row is set to its media or device functions. Hold Fn, or change the Fn lock setting.
Is it safe to clean a keyboard myself?
Yes, with compressed air and a barely damp cloth, after switching it off. Do not pry at a laptop keyboard or spray liquid onto it.
