My dell optiplex 360 model pc have built in speakers .I installed all the yhe audio drivers and analog drivers but no sound output .In the time of Using media player and video files only the video . No audio . WHAT I DO NOW ?

The optiplex 360 does come with internal speakers(it's in the spec sheet as optional), we bought them for our entire IT department and they worked fine on XP and vista, but when we put 7 on them, we can't get the internal speaker to work.

I'm sorry but the optiplex 360 does not come with internal speakers. To confirm what I'm saying you might ask a dell sales Agent on dells web site. I would suggest buying some external speakers to hook to the computer and see if you get sound through them.