Why my display and keyboard backlight is not work?

Both the keyboard backlight and the displays backlight will be driven by the same LED driver board.

Did you machine suffer from any liquid damage recently?

Generally, there is a short that causes this sort of issue. Resetting the SMC will be clearing any error logs that the logic makes during its pre-boot sequence, but if it keeps occurring, then there is more than likely either an over charge on the power line of the logic board (more than likely caused by corrosion on the board) or there is simply a component failure of the board itself.

Remove the bottom case and inspect the rear left of the logic board for liquid damage, as both the keyboard backlight and the eDP (the displays cable) connect on the rear left (by the left hinge when in operation. the same side as the magsafe connector and headphone jack)

I hope this helps.