Check what the top row is sending
Press F5 in the tester above. If the readout shows F5, the key works. If the brightness or volume changes and the readout shows nothing, the key also works, but the row is in media mode and is sending a media control the browser is not allowed to see.
Now hold Fn and press F5. If F5 appears, the row is simply inverted from what you expected, and the fix is a setting rather than a repair.
Pressing F5 with the tester focused will not reload the page: the tester deliberately lets refresh through so you do not lose a test run, but it swallows the rest.
Where the setting lives
- Many laptops toggle it with Fn and Escape, which is labelled Fn Lock and often has a small padlock icon on the Escape key.
- On HP, Dell, Lenovo and Asus machines the persistent setting is in the BIOS or UEFI, usually called Action Keys Mode, Hotkey Mode or Function Key Behaviour.
- On a Mac, the setting is in System Settings under Keyboard, and it controls whether the top row acts as standard function keys.
- On a custom keyboard, the mapping is in the firmware and can be changed with VIA or QMK.
When the keys genuinely do not work
If neither the plain press nor the Fn combination produces anything, and the rest of the keyboard is fine, treat it as a dead row. On a full size board the function row often shares a matrix row, so losing all twelve at once points at a trace or a controller pin rather than twelve failed switches.
If some function keys work and others do not, that is the ordinary single-switch failure case and the general troubleshooting page applies.
Software that steals function keys
Conferencing software, screen recorders and gaming overlays all commonly register global shortcuts on function keys, which then never reach the application you are using. The tester will show the key arriving normally, because the browser still sees it; the application simply never gets its turn.
If a function key works here but not in one specific program, look for a global shortcut conflict rather than a keyboard fault.
What the function keys traditionally do
These are conventions rather than rules, and nothing prevents an application from using a function key for something else entirely. If F5 does not refresh in one program, that is a choice the program made, not a keyboard fault.
| Key | Usual behaviour |
|---|---|
| F1 | Help |
| F2 | Rename the selected item |
| F3 | Find, or find next |
| F5 | Refresh |
| F11 | Full screen |
| F12 | Developer tools in a browser, Save As in some office software |
Function keys on a keyboard without a function row
Compact keyboards put F1 to F12 on a layer reached with Fn and the number row. Whether that layer produces a real function key depends on the keyboard firmware rather than on the computer, and this is worth confirming rather than assuming.
Hold Fn and press 1. If the readout shows F1, every application on the machine will receive F1 from that combination and the board is working as intended. If it shows Digit1, the layer did not engage, which is a firmware or a layer-key problem rather than a switch problem.