Hi, The most common problem in Windows for having no sound in a normal use its that you have on the automatic Windiows update, there is an updated that caused this problem, to resolved this download Aida64:
http
/www.aida64.com/downloads
install and identified the sound card, for example: realtek sound card. Then go to website of realitek website and download the driver for the sound card you have, or go to HP website and download the driver for your computer, install it and the problem is fixed.
Another cause of sound problem it´s that the .dll file is corrupt or damage, download Tuneup Utilities, install it and run, this programs corrects the most common registery files in Windows, then download CCleaner, its free, install and run, start with the first option; Clean run Analize and correct, the run the second option: Registry look problems and then repair. thats all.
In the case if you change the Windows version, the problem is that HP only have drivers for Windows 7 (64bits), http

/h10025.www1.hp.com/ewfrf/wc/softwareCategory?os=4063&lc=en&cc=us&dlc=en&sw_lang=&product=5128728. So you have to change for the original Windows 7 version because another version is not built for this computer.
So good luck and replay.