For specialized hardware like the Fn keys, brightness control, and battery management to work, you must install these in order: Drivers and Software updates for Laptop PC | Sony USA
Since Sony no longer provides active updates for this series, you must use a combination of official archives and generic drivers. 1. Sony Support Archives Visit the Sony USA Support Page or Sony Asia Pacific and enter your (not PCG-81114L sony vaio pcg81114l drivers windows 10 install
Before installing Windows 10, ensure your hardware is ready. : The PCG-81114L For specialized hardware like the Fn keys, brightness