Test the pad
Press every key on the pad in the tester above. Watch what the readout names. Numpad4 means the pad is sending digits; ArrowLeft from the same physical key means Num Lock is off.
The number pad keys report separately from the digits along the top of the keyboard, so a working Numpad7 and a working Digit7 are genuinely two different results.
Num Lock
With Num Lock off, the number pad reverts to its secondary functions: arrows, Home, End, Page Up, Page Down, Insert and Delete. This is the original purpose of the pad and it is still the default state on some machines at boot.
Press Num Lock once. If the keyboard has an indicator light, it should change. Some keyboards have no light at all, which is why the tester is more reliable than looking at the hardware.
Mouse Keys
Both Windows and macOS include an accessibility feature that turns the number pad into a mouse pointer control. When it is on, pressing pad keys moves the cursor instead of typing digits, and nothing about the keyboard looks wrong.
It is often enabled by accident, because the shortcut on Windows involves holding Left Alt and Left Shift and pressing Num Lock. Turn it off in accessibility settings.
Hardware causes
- On a laptop with an overlaid pad, the pad only exists while Num Lock is on, and on some models only while Fn is held.
- A separate USB number pad is its own device: check it on another computer before blaming the machine.
- The whole pad dead on a full size keyboard, with the rest fine, suggests a trace or connector rather than seventeen failed switches.
- Liquid damage frequently kills the pad first on a desktop keyboard, because it sits at the low end of the slope on most cases.
The pad types digits everywhere except one application
If the tester shows Numpad4 sending a 4 but a particular program disagrees, the program is treating the pad keys as distinct from the digits along the top row, which they genuinely are. Accounting software, point of sale systems and some remote desktop clients all do this, and a few of them only accept the top row.
Remote desktop sessions are the most common version of this. Num Lock state is tracked separately by the host and the client, and the two can disagree, which produces a pad that types digits locally and arrows remotely. Toggling Num Lock inside the session usually resynchronises them.
Testing a separate USB number pad
A standalone pad is a keyboard in its own right as far as the computer is concerned. Select the full size layout here and press its keys: they report exactly as a built-in pad would, so the same Num Lock logic applies.
If nothing arrives at all, try it in another port and on another machine before anything else. A pad that works elsewhere points at the port or the computer, and a pad that works nowhere has almost certainly failed, at which point the economics rarely favour repair.