Same problem here. I think it started after the most recent Win8 auto update. I have not updated to 8.1. I have a toshiba satellite. I turn on the computer, no sound, restart, then it works. I tried system restore and that doesn't work either. I did a virus scan and no problems there. I might have to do a full system recovery, but I really don't want to do that.
There is no hope in Windows. I decided last year soon after getting this Win8 monstrosity that I am DONE with windows. After 20 years, I am DONE with this company. They screwed so bad with the people who have stuck with them over the years (me).