Windows Media Player

Hi When i am trying to play the WMP i am getting the message "Windows media player cannot play the file as there is a problem with your sound device. there may not be a sound device installed on your computer, it may be in use by another program, or it may not be functioning properly".

I am unable to play any other music, make skype calls. Sound system is fine, that is have tested.

Please help me resolve this problem.