A restart is mandatory for the driver to bind to the system hardware.
Sony no longer provides a single "one-click" download for all models, especially for older Windows 7 systems. To find the correct files for your specific laptop: Official Sony Support Personal Computer page Enter your Model Name sony vaio assist button driver download link
Identify your VAIO model and OS
If you absolutely cannot find a working driver for your exact model, your final resort is to restore the laptop using Sony’s original (ISO images can be found on archive.org). Those discs contain the complete, factory driver set—including the working Assist Button. A restart is mandatory for the driver to
Pressing the button instantly launches VAIO Care (typically within 5–10 seconds). From there, you can perform tune-ups, defragment your hard drive, and run hardware or software diagnostics. Finding the correct Sony VAIO Assist button driver
Finding the correct Sony VAIO Assist button driver is a common challenge for users who have upgraded their operating systems or performed a clean install of Windows. The Assist button is tied to the Sony VAIO Care software suite, and without the proper underlying drivers and system components, the button remains unresponsive.