No audio device when opening volume - Win XP

Hello,
I have no longer audio on my Dell C610, Win XP SP2, Media Edition.The speakers work, I can hear the usual beep before booting of Win (this is because battery is dead, power has been down here in this country a lot and the system warns me that time of day is not set properly). In config panel all audio devices are said to be working properly with drivers installed. I have uninstalled both Codecs audio and Crystal WDM Audio Codec. And rebooted. That did not work. I then found in this forum that the volume may be down (the volume button in the system tray on the taskbar was lost actually at the same morning that there was no longer audio) and went into Config panel, according to the post ''Activating Volume Control in the taskbar" in this forum. Then I see in this window ''Sounds and AUdio Devices Properties' the tab Volume completely grayed out, and it says on the top field 'No audio device', the volume is down all the way and nothing can be adjusted or touched. I'd be happy to hear any of your advices. I already search on Dell's site, no answers. I did a driver detection of my Dell on touslesdrivers.com, (this is a French site as my OS is in French) and it detected drivers properly installed for both mentioned above (I don't know what these are, one audio card and one xxx ?) Please respond. Thanks, Akke