How do I get sound running again in Sonar?

Hi,
 
A message came up when Sonar booted:
"There are no audio devices for the current driver model on your system.  Please go to EDIT/PREFERENCES/AUDIO/PLAYBACK RECORDING and choose a different driver model."   The current model that doesn't work is "MASTER".  
 
There are not any devices listed in PREFERENCES.
 
The sound works on everything on my computer, except in Sonar.
 
What is "MASTER" and how is it fixed?  Above "MASTER" it says "none".  I don't know how or what to change "none", to something that makes the master bus work again.
 
Another message came up:
"The following tracks and buses are currently assigned to a silent hardware output.  The items listed below will be silent in your project until outputs are reassigned to a hardware output."
 
thanks for help,
wadrum