I've moved your thread to the Computer Help section.
I would think that 4th Aug. is a bit too far to go back for your restore points if that was when you noticed this PuP.
I've seen where an unwanted program had taken out the audio on a laptop, but running AdwCleaner removed whatever it was and restored the audio.
That had also been picked up while on FB.
Should that FB program have left some residue which is causing this problem for you, download AdwCleaner to see if it can find anything.
In the main window during the scan, it may find legit programs it considers as unwanted/adware but you can uncheck the boxes for those if any that you want to keep.
https://www.bleepingcomputer.com/download/adwcleaner/Instructions are lower down the page.