screen brightness cannot be adjusted with windows 8 using Sony Vaio

Hi John,

Welcome to Microsoft communities.

 As I understand that you are not able to adjust screen brightness Windows 8.

1.       Did you make any recent changes prior to the issue?

2.       Do you get any error message/code?

3.       Are you specifying to the monitor settings or the settings in Windows 8

Method 1:  Enable adaptive brightness

1. From the Start Screen, type Control Panel and select the Control Panel.
2. Set the View by: dropdown to Category
3. Select Hardware and Sound.
4. Select Power Options.
5. Select the Change plan settings link on your current power plan
6. Select Change advanced power settings
7. Expand Display
8. Expand Enable adaptive brightness
9. Change the setting to On and select OK.

Method 2: Download and install the latest drivers/ utility software’s from the manufacturer’s website.

http://esupport.sony.com/US/perl/select-system.pl?DIRECTOR=DRIVER&PRODTYPE=24

If the drivers are not available for Windows 8, download for Windows 7 from your manufacturer’s website and install in Windows 7 compatibility mode:

a) Right-click on the driver and click on ‘properties’.

b) Click on the ‘compatibility’ tab and check the box ‘Run this program in compatibility mode for’ and select Windows 7 operating system from the drop down.

c) Click on ‘Apply’ and click ‘OK’ and run the file to install it.

Please post back if you are still experiencing the issue. I will be glad to provide you with additional options available that you can utilize to get this issue resolved.

Method 3: Run SFC scan

1. Type Windows key +W
2. Command Prompt (Admin)
3. Type cmd
4. At the Command Prompt, type: sfc/scannow

This will check for any integrity violations. Restart your system

For reference:

Power plans: Frequently asked questions

http://windows.microsoft.com/en-US/windows-8/power-plans-faq