direct sound test; results: failure

I downloaded Realplayer (it works fine). However now there is no sound for windows media player or for any website that I visit. Only sound for Realplayer. I ran dxdiag for direct sound test and it displayed: Results: Failure at step 19 (user verification of software): HRESULT: oxoooooooo(error code).

I am not computer literate. How do I resolve this? Please any help appreciated. p.s. also no sound for computer sounds, like pop-ups, etc.

 

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