Run these in order — cheapest first

Laptop keyboards fail differently than desktop ones: the keyboard is a ribbon-cabled component buried under the chassis, the switches are delicate scissor mechanisms, and software — especially the Fn layer — fakes hardware failure constantly. Work top to bottom and stop when it’s fixed.

Step 1 — The 60-second software checks

• Restart. Not sleep — a real restart. A hung keyboard driver or a crashed input service is the most common cause of total keyboard failure.
• Num Lock / Fn layer. Letters typing numbers = Num Lock. F-keys doing brightness/volume instead of F1–F12 = Fn Lock. Both look like broken keys and both are one keypress from fixed.
• Filter Keys / accessibility. Windows Filter Keys ignores brief and repeated presses — a keyboard that ‘sort of works’ with dropped letters is often this. Check Settings → Accessibility → Keyboard.
• The tester. Press keys on the tester. Keys that light are reaching the OS — if the internal keyboard lights everything but your app still sees nothing, it’s the app.

Step 2 — Bisect with an external keyboard

Plug in any USB keyboard. If it works perfectly while the internal one doesn’t, software is nearly exonerated — the fault is in the internal keyboard, its cable, or its connector. If both fail the same way, it’s OS/software, not hardware.

In Device Manager (Windows) or System Information (macOS), check the keyboard appears without errors. Uninstalling the device and rebooting forces a driver re-detect — a legitimate fix for weird post-update failures.

Step 3 — Clean before you open anything

Shut down, unplug, tilt the laptop so debris falls away from the chassis, and blow short bursts of compressed air along the key rows. Lift a single problem keycap only if you’re confident — scissor clips snap, and a snapped clip means a wobbly keycap forever. A sticky key after a spill needs more than air: a barely-damp isopropyl swab around the mechanism, then full drying time.

Step 4 — The ribbon cable

If a cluster of keys died after a bump or the keyboard works only when you hold the chassis a certain way, the ribbon is the suspect. On many laptops it’s reachable by removing the bottom cover: a flat cable into a ZIF socket with a flip-up latch. Power off, disconnect the battery if accessible, unlatch, reseat squarely, relatch. This single step revives a large share of ‘dead keyboard’ laptops — but on models where the keyboard is sandwiched under the motherboard, it’s a bigger job; check a teardown guide for your exact model first.

Step 5 — Damage assessment

• Spill recently? Corrosion on the membrane traces kills whole regions and grows over days. Time matters — powered-off drying helps the laptop, but the keyboard’s printed membrane is usually the casualty.
• Row or column of keys dead — a broken matrix line; that’s a keyboard replacement, not cleaning.
• Random scatter of dead keys — worn dome contacts or liquid damage spots. Same conclusion on most models.

Step 6 — The honest cost math

Replacement laptop keyboards run $15–60 for parts, but many modern laptops integrate the keyboard into the top case — meaning ‘keyboard replacement’ is really ‘top-case assembly’, which is pricier and more labor. Check your model’s construction before buying parts. And keep the pragmatic option on the table: a $20 external keyboard restores full function in zero minutes — sometimes that’s the right fix, especially on a machine nearing replacement anyway.

Frequently asked questions

Why did my whole laptop keyboard stop working at once?

Total failure is rarely hardware on all keys at once — it's usually software (a crashed driver or Filter Keys), a locked function state (Fn+Lock), or the keyboard ribbon cable losing contact. Restart first: it fixes a stuck driver more often than anyone admits. If a restart doesn't help, an external USB keyboard working fine while the internal one is dead points at the internal keyboard's connection or the keyboard itself.

Some letters type numbers — did my keyboard break?

No — Num Lock is on, and your laptop shares the numpad onto letter keys (typically 7/8/9, U/I/O, J/K/L). Toggle Num Lock (sometimes Fn+NumLk or Fn+F11) and the letters come back. It's the single most common 'broken keyboard' report that isn't broken.

Can I clean under laptop keys myself?

Carefully. Most laptop keycaps can be lifted with a thin plastic pick — but the scissor mechanism underneath is fragile and cap clips break easily, so only pull caps you're willing to risk. Safer: shut down, tilt the laptop, and use short bursts of compressed air across the key rows. Never use liquid cleaners on a powered laptop and let it dry fully after any damp cleaning.

How do I know if it's the ribbon cable?

Clues: the keyboard failed after a drop, a hinge-area knock, or a previous repair; a whole region or cluster died together; or the keyboard works when you press near the cable entry point / flex the chassis slightly. Reseating the ribbon is a 15–30 minute job on many models — a small ZIF connector under a flip-up latch. If you're not comfortable inside the chassis, that's a cheap repair-shop job, not a new-laptop problem.

When do I actually need a replacement keyboard?

After a spill that left corrosion, when a whole matrix line is dead (a row or column of keys, not a scatter), or when keys remain dead after cleaning and a ribbon reseat. On most laptops the keyboard is part of the top case or held in by dozens of plastic rivets — check a teardown for your model first; sometimes the honest answer is an external keyboard, which costs $20 and zero surgery.