HP 650 Audio :: Notebook Has No Sound - Spotify Says Something About Sound Card Not Working?

Okay, well the day before yesterday I was trying to watch Youtube but when I clicked on a video it had no sound. I thought it was Youtube, so I exited the site and thought I'd wait a little bit. So then I went to Spotify to listen to some music. I kept clicking and clicking and nothing was happening. Then I noticed a blue notice at the top that said something about my soundcard not working properly.

I then checked everything on my computer to see if it had sound. Windows Media Player...no, videos on Facebook...nope, nothing was working. At first I thought it was my daughter. I let her watch Youtube when she lays down for a nap. I came in the other day and she was hitting all kinds of buttons on my computer. I stopped her though and everything seemed fine. I also remember my computer updating that day. Could it be that something went wrong with the update? I don't know if that's possible or not.
 
And also, what is a soundcard. Do I have to buy it or do I download it???
 
I went to Yahoo answers and someone said to uninstall the drivers. I did that and then reinstalled them and it worked. The rest of that day I had sound on everything except for Facebook. Yesterday night it happened again and the sound has not returned since but my computer sounds are still working. When I logged on the computer made the log in sound it usually makes. I also tried to listen to a video with headphones and it still did not work.  Again, I uninstalled the drivers and then re installed them and got nothing.