No sound from my computer!!!

Hello,
I am no longer getting any sound from my computer. The most it does is beeps when other sounds are suppose to be made. When I go to Windows Media Player this message appears: "Windows Media Player cannot play the file because there is a problem with your sound device. There might not be a sound device installed on your computer, it might be in use by another program, or it might not be functioning properly." I have tried all the Windows Media Player troubleshootings...what is wrong?