I wish I could help, but I cant really because you gave little information... If I were you, I would look in your crash log record, which pops up on screen after minecraft fails to launch. Read it over somewhat carefully. Depending on how long the text is, I find usually it says why your launch went wrong towards the bottom.
Though I am confused, what does "does not launch" mean? Does it crash, or come up with a message? If there is a message, I know how to fix it usually, seeming as I have gotten it before, it saying a certain mod needs at least a certain version and up to run. And the no sound, that happens just as an error, all you need to do usually is reload the game until the sound comes back, if that doesn't work just restart your computer.
