need more info.
What type & version of operating system. Is this a multi-media PC? What is the brand & model? Is a plug pulled?
Rule of thumb: the last thing(s) you changed (update, new app, etc. is the first thing to suspect.)
Have you made ANY change before it went bad?
I had just turned on my computer today, and it says that i have to install multimedia audio controller. Now i have no sound on anything. Ive had the same computer for about 2 years and nothing like this have ever happened. My sound has always worked. How do i fix this problem?