Sound On My Computer Deleted?

So my little kid was on my computer and he deleted a program and after he deleted the program sound wouldnt come from my computer, and there is no speaker icon in the bottom right corner anymore, so I think he deleted the sound program or whatever? whats the program called and how do I get it back?

 

Maybe he deleted the driver, try restore your computer to yesterday or the closest time your computer has saved in system restore.