No sound

First, has the sound ever worked?  Second, if you connect a headset to either the front panel headphone jack or to the rear GREEN speaker jack do you get any sound?

If it did work originally, but doesn't now is this something recent, after installing or uninstalling something or did you do a complete reinstall and now it won't work?

Are you using the Dell supplied audio drivers? if not that could be one problem.

Lots of questions to so we can try and assist you. 

Hi, thanks for the response.

No, I have never heard sound from the computer.

Yes, headphones connected to the front panel work fine.

I have recently changed monitors (from Dell 1907 to Dell 2008), but have never had sound from either on this computer.   (The monitors were fine with other computers).

Yes, I have all Dell drivers and one of the actions I took to resolve the problem was to download all the latest drivers from Dell.

Any further thoughts ?

One thing I missed on my first response.  I assume (maybe I shouldn't) that you have powered analog computer speakers (ones that have their own built in power amplifier) connected to the GREEN speaker jack on the rear.  There is no internal speakers in the PC tower.  Most monitors do not have built in speakers.

You can check the GREEN speaker out jack on the rear of the PC by plugging the headphones into that jack.  If there is sound there, the PC's sound is working correctly.

I had a similer problem on a Dell Dimension 5150/e510  this is what I did, Restart the computer, and when the computer is rebooting, (when the DELL loading screen shows up) press F2 to go into bios, use the KEYBOARD's up and down keys and find intergrated audio, make sure that and anything else audio related is enabled. 

sampa64, the user is getting audio at the front panel headphone jack so the Integrated audio is enabled in the BIOS.