Keyboard keys not working: how to find the cause

Step 1: find out how much is affected

Open the keyboard test and press every key slowly, one at a time. Keys turn orange while held and green once released, and List keys not tested yet shows what is left. The pattern you see points to different causes:

• One key never lights up: usually the switch, the keycap mechanism or dirt under that key.
• A group of neighbouring keys fails, or a whole row: often a damaged circuit inside the keyboard, typical after a spill, or a loose internal ribbon cable on a laptop.
• Keys light up in the test but do nothing in your app: the keyboard works; look at the app, a shortcut or a setting (step 4).
• Nothing lights up at all: start with the connection (step 2).
• A key works only when pressed hard or at an angle: a worn membrane, a dirty switch or a sticking stabiliser on long keys such as Space, Shift and Enter.

Step 2: rule out the connection

• Wired keyboards: plug directly into the computer instead of a hub, dock or adapter, and try another port. A detachable cable can fail on its own, so try a spare if you have one.
• Wireless with a receiver: replace or charge the batteries and move the receiver to a port near the keyboard, away from metal and other receivers. Missing letters while typing fast is a classic sign of a weak battery or signal.
• Bluetooth: turn Bluetooth off and on, remove the keyboard from the paired devices and pair it again. Keyboards paired to several devices may still be connected to another one.
• Try it elsewhere: the same keyboard on another computer, or another keyboard on this computer. Whichever one keeps the problem is the one at fault.

Step 3: check the settings that switch keys off

• Filter Keys (Windows: Settings > Accessibility > Keyboard) ignores brief or repeated presses, so quick taps can seem to vanish. Slow Keys on a Mac (System Settings > Accessibility > Keyboard) does something similar.
• Sticky Keys makes Shift, Ctrl, Alt and Command latch after one press, which can look like a stuck modifier.
• Gaming keyboards often have a game mode or Windows-key lock, toggled with a key combination or in their software, that disables the Windows key and sometimes Alt+Tab.
• Laptops: the function row may send media or brightness actions instead of F1–F12. An Fn lock key or a setting in the laptop's own software or firmware changes this.
• Remapping software: keyboard utilities and remapping tools can disable or reassign keys. Quit them, or test on a computer where they are not installed.

Step 4: one app or everywhere?

If a key works in the keyboard test but not in a particular game or program, the keyboard is reporting it correctly. Check that program's key bindings, whether it expects a different layout, and whether another program running in the background has grabbed the shortcut. Some keys and combinations are taken by the operating system before any app sees them, for example Ctrl+Alt+Del on Windows or Cmd+Tab on a Mac; a browser test cannot see those either, so a missing light for them is not a fault.

If a key types a different character from the one printed on it, that is usually a layout problem rather than a dead key: see keyboard typing wrong symbols.

Step 5: a stuck key, or a key that keeps typing

• A key stays orange in the keyboard test after you let go: the release was not received. Press it again. If it keeps happening, the key is physically sticking or the switch is not opening; look for something under the keycap.
• A dashed border means the page lost focus while the key was held, not that the key is stuck. Press it again with the test window active.
• A key types twice or keeps repeating without being held: see keyboard typing double letters and the chatter test.
• Shift, Ctrl or Alt seem stuck in every program: check Sticky Keys first, then press both the left and right versions of the key in the keyboard test to see whether one side is held down.

Step 6: dirt, spills and repairs

• Crumbs and dust: disconnect the keyboard, turn it upside down and use short bursts of compressed air around the affected keys.
• After a spill: disconnect it at once (shut down a laptop and unplug it), turn it upside down and let it dry completely before testing again. If liquid may have reached the inside of a laptop, have it checked rather than powering it on repeatedly.
• Mechanical keyboards with hot-swap sockets: a bent switch pin or a switch that is not fully seated is a common cause of a single dead key after cleaning or swapping switches. Reseat it carefully, or swap it with a switch from a key you rarely use to see whether the fault moves.
• Laptop keyboards: several dead keys in a pattern after a drop or a repair can mean a loose internal connector, which is a job for a technician or the manufacturer.

A browser test shows which keys reach the computer; it cannot repair a switch, a circuit or a driver. If a key on a recent keyboard fails in every test, on every port and on another computer, note which keys fail and contact the seller or manufacturer.

Which test to use next

• Keyboard test: check every key, with ANSI, ISO and Mac layouts.
• Numpad test: the number pad and Num Lock, if numbers turn into arrows.
• Keyboard ghosting test: keys that only fail when several are held together, as in games.
• Keycode tester: the exact key value and code a key sends, useful when a key reports as something else.
• Keyboard test results explained: what each colour and message means.