Why Won’t My Computer Play Sounds Anymore?

Mary from Tallahassee, FL writes:

A few months ago, my computer lost its ability to play sounds (yes, I have been mute for that long). Over that time I've checked everything I can find that appears to have anything to do with sound. Every device, driver, etc. states that they are functioning properly. Still I have no sound. Do you have any idea what could have caused me to lose sound or how to fix it? Any light you can shed on this problem will be most appreciated. Answer: Use this tip to troubleshoot audio problems when your computer's sound goes out.