BIOS is outdated – This issue was seen in several BIOS versions.Here we can change the registry keys or create new ones to fix the issue. Windows has mistakenly disabled this combination – This can occur after an update or an upgrade as a registry entry changes its state.Fn Lock is turned on – Your keyboard settings might always be set to always pretend the Fn key is being held when using the F1-F12 keys which actually controls some other settings.