almost imposible to say with the informations you provide.
One thing that could have happend, is that your sound setup is chosen as 'dummy'.
Go to edit | Settings
chose Audio Settings
make sure the selected interface is SDL
in a more advanced angle..
Currently ASIO is not working. if you somehow have ASIO as default sound choice for your sound hw, you wont have sound..
You would have to either reconfigure your sound device or create a new profile.
Lastly you would have to test your directx.
open the cmd-editor and type dxdiag and test all sound components. You should however have sound problems in other programs if your problem lies in directx. does all other sound replay work correctly?
br