The LIFX White Restore* feature returns your LIFX lights to default white via wall switch:
Flick the wall switch off
Flick the wall switch back on for about 1-2 seconds
Flick the switch off again
Flick the switch back on
This will return your lights to the default 100% brightness on 3500K white, without an app, or voice control. They will be able to be controlled via voice, and the app, within a few seconds after this light switch change.
*Requires latest firmware for LIFX Original, LIFX White 800, White 900 and LIFX Color 1000 model lights.
*Requires LIFX and LIFX + firmware 2.76 or later and LIFX Mini bulb firmware 3.41 or later.