After reinstallation of Win. XP sp2 my PC has lost sound.It is a 1.8 GHz P-4 machine having intel D845 GLVA mobo and onboard sound graphics. There is no add-on sound card. All other functions of the PC are OK. The summary of my investigations is as follows: 1)audio is enabled in BIOS and Windows audio service is started under Services. 2)There is no YELLOW exclamation mark in Device Manager. All the drivers are installed and all the devices are properly. Under Sound ,video and Game Controllers the device is shown as Sigmatel C-Major Audio and the driver is STAC 9750. No problem is found on running Intel's Driver Update Utility. 3) In system Information section there are no problem devices and conflicts. 4)However when dialog box of Sound and Audio Devices under Sound Speech and Audio Devices is opened it shows that default Audio,Sound Playback & Recording Etc Devices are not present. 5) The Direct X (9)Diagnostic tool says that there are neither sound devices nor drivers. The Note at the bottom says that there is no sound device. If one is expected then install the drivers. 6)The PC also does not play Windows sounds and all sound sliders at the minimum and immovable.Now Syschat Forum experts are requested to elaborate reasons for lost sound and more importantly guide me how to regain sound of my PC. Thanx in advance.