I have a Sony laptop and I want to turn keyboard back-light off. It doesn't have a shortcut function key for doing this on the keyboard . I can turn off it with VAIO Control Center in Windows but I don't know how can I turn it off in Ubuntu 14.04.

There isn't available to me: /sys/devices/platform/sony-laptop/kbd_backlight doesn't exist on my machine.

I have this folder /sys/devices/platform/sony-laptop/ and there is three folder one power folder and two shortcut-ed folder driver , subsystem and five file contains battery_care_health , battery_care_limiter , modalias , touchpad and event

This is the output of running sudo modinfo sony-laptop:

filename:       /lib/modules/3.13.0-34-generic/kernel/drivers/platform/x86/sony-laptop.ko
version:        0.6
license:        GPL
description:    Sony laptop extras driver (SPIC and SNC ACPI device)
author:         Stelian Pop, Mattia Dongili
srcversion:     5C6E050349475558A231C59
alias:          acpi*:SNY6001:*
alias:          acpi*:SNY5001:*
depends:        
intree:         Y
vermagic:       3.13.0-34-generic SMP mod_unload modversions 
signer:         Magrathea: Glacier signing key
sig_key:        50:0B:C5:C8:7D:4B:11:5C:F3:C1:50:4F:7A:92:E2:33:C6:14:3D:58
sig_hashalgo:   sha512
parm:           debug:set this to 1 (and RTFM) if you want to help the development of this driver (int)
parm:           no_spic:set this if you don't want to enable the SPIC device (int)
parm:           compat:set this if you want to enable backward compatibility mode (int)
parm:           mask:set this to the mask of event you want to enable (see doc) (ulong)
parm:           camera:set this to 1 to enable Motion Eye camera controls (only use it if you have a C1VE or C1VN model) (int)
parm:           minor:minor number of the misc device for the SPIC compatibility code, default is -1 (automatic) (int)
parm:           kbd_backlight:set this to 0 to disable keyboard backlight, 1 to enable it (default: no change from current value) (int)
parm:           kbd_backlight_timeout:meaningful values vary from 0 to 3 and their meaning depends on the model (default: no change from current value) (int)

With the suggested command:

sudo modprobe -r sony_laptop
sudo modprobe -v sony_laptop kbd_backlight=0

Output was:

insmod /lib/modules/3.13.0-34-generic/kernel/drivers/platform/x86/sony-laptop.ko kbd_backlight=0

It doesn't seem to affect the keyboard backlight.
And also trying this command:

sudo modprobe -v sony_laptop kbd_backlight_timeout=3 kbd_backlight=0

and doesn't seem to effect the keyboard backlight I also test it after restart laptop, And I didn't see any effect too.

Important : By default, keyboard backlight is off; when I press a key it turns on and after 15 seconds it turns off again. It's the same result on battery and AC power

I followed also http://ubuntuforums.org/showthread.php?t=2139597 and
Keyboard backlighting not working on a Vaio VPCSB11FX but didn't work so.