Warning!!! Tech Support will refuse warranty service for speaker problems if the VLC media player is installed on the laptop. This exclusion is NOT disclosed in the laptop warranty! Remove all players before contacting Tech Support, leaving only Windows Media Player.
As ridiculous as this sounds, I stubled upon a remedy from a fellow blogger. In order to fix the sound on my Dell Inspiron laptop, power it down, then PULL THE BATTERY for 10 seconds, restart the computer, problem solved... for real!
Up to that point, I literally spent two days unistalling and reinstalling software and hardware, then 4 hours on the phone with a third party support service, who insisted it was defective hardware. My persistence in seeking a solution paid off, and in this case unbelievably simple.
Headphones now work well also! Give it a try!