Sound quit working on my vizio sv422xvt. What replacement part do i need to fix it?

Check whether the audio is muted by accidental press at remote control button. Enter its sound menu, and check it. If muted, as you know there will be no audio output. If not muted, Check the speaker/s. If found OK; check and replace the damaged component/s at its audio output section circuit board. If needy, replace this board as card basis. If you wish to get some details; check the site linked here. Pull up older posts. Search the site by type in the "brand name" to your device; in the "Search box at the top right of the display window of the Homepage" to get gathered related posts. http://electro-medical.blogspot.com/