If you are trying to reinstall Windows 7 on your Sony Vaio PCG-71315L, you may have run into a common headache:
Sony no longer hosts official VAIO drivers (Sony eSupport closed in 2015). You’ll need to rely on and manual installation methods . sony vaio pcg 71315l drivers for win7
For a clean Windows 7 install, you must install these in order to get hotkeys (brightness, volume) and special features working: If you are trying to reinstall Windows 7