no sound

I have a sistem manufacture:RS480 But on the Mianboard says RS482-M.A Precesor aMD Athon (TM)64 Proccesor 3200 +200GHZ, Memory 478Mb RAM. A Display ATI Radeon Xpress Series 200
Everything looks Ok. Realtek AC 97 Audio, the driver the volume and sound effects but no sound come uot from my speakers. I did a Direct Sound test result: Failure at step 19 (user verifacation of sofware): HRESULT=0X00000000(error code) I will apreciate your help