How to find a key that sometimes stops working

A key that works most of the time can be hard to diagnose. It might miss one press, work again after a pause, or fail only in a particular app. A single successful press does not rule out an intermittent problem.

Use the Keyboard Test to check the problem key repeatedly and compare it with the rest of the keyboard. Then use the results to decide whether to check an app or setting, clean the keyboard, or arrange a repair.

Test the key repeatedly

1. Open the Keyboard Test in your browser. Click the test area if needed so it can receive your key presses.
2. Press the problem key 10 to 20 times, with a short pause between presses. Watch for a response on the test's keyboard display each time.
3. Test several nearby keys in the same way. Then press the problem key while holding a nearby key, if that combination is something you normally use.
4. Repeat the check after using the computer normally for a few minutes, especially if the failure only happens when the keyboard is warm or after typing for a while.

Press the key normally rather than striking it harder than usual. If the problem only happens in one program, also try typing in a different app, such as a plain text editor. This helps separate a keyboard problem from a shortcut or setting in that program.

What the result means

The key responds every time in the test

The keyboard is sending presses to the browser during this check. If the key still fails in one app, check that app's shortcuts, input field, and settings. If it fails only after a long hold or repeated presses, check the keyboard's repeat settings and any accessibility features below.

The key misses some presses in the test

The issue is probably below the app level. Debris, a worn contact, a loose connection, or a failing switch can cause a key to work inconsistently. Try the quick checks below, then test again.

A group of nearby keys fails

Several keys failing together can point to a connection or keyboard circuit problem, especially on a laptop. If there was a spill, stop using the keyboard and follow the manufacturer's advice. Do not keep pressing keys to see whether they recover. See what to do when laptop keys stop working after a spill.

A special key does not respond in the browser

That alone does not show that the key is broken. The Fn key never reaches the browser. The Windows key, Print Screen, and laptop shortcut keys for brightness, volume, or Wi-Fi are also usually handled by the operating system before the browser can see them. Test ordinary letter and number keys to check the keyboard itself.

How to fix it

1. Check for a stuck or obstructed key. Turn the keyboard off or disconnect it, then look for crumbs or dust around the key. Use a soft brush or gentle air, and avoid spraying liquid into the keyboard or prying off a laptop keycap.
2. Reconnect the keyboard. Unplug a wired keyboard and connect it again, preferably to another USB port. For a wireless keyboard, check its battery or charge, reconnect its receiver, or pair it again.
3. Check accessibility settings. In Windows 11, open Settings › Accessibility › Keyboard and check whether Filter Keys is on. On a Mac, open System Settings › Accessibility › Keyboard and check Slow Keys. These features can change how brief presses are accepted.
4. Check key repeat settings. If a key works when tapped but not when held, or repeats too slowly, check the keyboard settings. On Windows 11, open Settings › Accessibility › Keyboard. On a Mac, open System Settings › Keyboard and adjust the key repeat options.
5. Restart and test another app. A restart can clear a temporary input problem. If the key works in the test and other apps but not in one program, check that program's key bindings or update it.
6. Try another keyboard. Connect a different keyboard to the same computer. If it works reliably, the original keyboard is the likely cause. If both keyboards have the same problem, look for an operating system or connection issue instead.

When it's probably a hardware problem

If the same key continues to miss presses in the Keyboard Test after cleaning and reconnecting, test the keyboard on another computer if possible. A keyboard that fails in the same way on two devices likely has a worn or damaged switch, membrane, or cable.

For an external keyboard, replacement is often simpler than repair. For a laptop, check the warranty before arranging service. Some laptop keyboards can be replaced separately, while others are built into the top case and cost more to repair.

Why the browser may not see every key

A browser test checks the key presses that the browser receives. The operating system can intercept special keys first, so a missing response for a system shortcut is not a reliable hardware diagnosis. The test also cannot reproduce every situation, such as a specific app's shortcut handling or a key that fails only after extended use.

For a useful comparison, test ordinary keys several times, then compare the same keyboard in another app or on another device.