No Sound in SPLAT project

Hey Guys:
I opened a project today and when I hit "play" there isn't any sound.  The transport move fine and the meters are clearly moving, so I know what's been recorded is still there but I just can't here it.  Other projects I tried play fine.  I know I have accidently clicked something.  Does anybody have an idea what it could be?
 
Thanks as always.

1) Do other projects play?
2) Check the routing assignments to make sure your Master is outputting audio to your audio interface
3) Is there any possibility that Sonar is competing with another application (or Windows) for access of the audio interface? (particularly if using ASIO)
4) Is your Driver Mode set as intended?
5) Is it possible some 3rd-party 32-bit plugin(s) are present, and potentially breaking things like playback of audio for the whole project?  (weird and funky things sometimes occur when bridging 32-bit plugins).
 
There are likely additional kinds of simple things that could be added to the above list, so please give some thought to other kinds of stuff you can check that are straight forward and simple.  I will move on to something a little more involved.
 
It would be possible that for whatever reason, your project COULD be compromised/corrupted in some fashion, particularly if it is indeed only this single project exhibiting this behavior of not producing audio when the meters are clearly showing that SONAR believes it is producing audio.
 
Soooo, with the above in mind, I would suggest you try one simple method, and if that doesn't work to fix the issue, move on to the 2nd.
 
Firstly, try just doing File>Save As, saving the project with a new name, but still in the same Project Folder.  The newly created project file (CWP) would still reference any existing audio clips from wherever they were already located - this is just a simple test to see if perhaps something a little messed up could maybe get fixed by saving it again under a new name.  A variation on this would be to do the File>Save As, but this time actually create a brand new Project Folder that matches the new name you give the project file you are creating, and make sure to also check the Copy All Audio option, so that it also brings over any referenced audio clips to the new project folder (so that the new project is self-contained, and not pointing at audio that lives in the old project folder).  Sometimes one of these two variations will result in a project coming back from the dead, so to speak.  I do not know why it sometimes works, and why sometimes it doesn't.
 
Secondly, if the above didn't work, you could try starting with the original project loaded, the one that doesn't play, and exporting tracks or groups or tracks as track templates, and then creating a new project and inserting everything from the track templates you had created.  That will pretty handily carry over all your track and bus settings, and any soft synths and all of the routing.  Then, you would need to bring over any recorded midi clips, and then maybe export audio clips as Broadcast Wave files, so they would properly get positioned when imported into the new project build from the old nonplaying project.
 
There are likely more sophisticated methods of building a new replacement project from all of the bits of the non-functional original project, so if anyone else has better ways of doing that, please by all means jump in.  I haven't had to deal with any project corruption for several years now, so at best I am extremely foggy with my memory, other than that for one project, I was indeed able to resurrect it all by manually building up a new project and populating it from the original.
 
Bob Bone