How to fix IDT High Definition Audio CODEC problem?

Okay, so my brother like fixed our computer and made a new admin account and when I came on, I noticed the sound was on mute. I scrolled over it and it said No Audio Output Device is installed!!! So I went to the device manager on the control panel and next to the IDT High Definition Audio CODEC it had the yellow caution triangle thing. After trying to troubleshoot the problem, it is still not fixed. When I tried to update it, it says that I have the best and latest version. When I try to roll it back, I can't...it doesn't allow me to click that button...PLEASE HELP!! I need to watch my naruto!!