Did you start the project in X3?  I opened up a couple of projects in X3 that I started in X2 and nothing plays until I bypass every effect bin, effectively disabling all my plugins.  Then it plays.  I haven't gone through all of them one at a time to find the offender but that's what's happening when I have this happen...

you mucked about with the front dial ? there is an input / output dial on it...
 
preferences maybe ya best bet though.. making sure it's in asio mode etc..
 
my interface has multi outs, but if I don't hit the other 2 on the button the asio driver won't work.. so make sure yours hasn't got something simular.. also see if there is a control panel for it by the clock on the bottom right of ya screen.
 
 
if you moved usb ports , that might be the issue.. so do a reinstall.. my micro-korg is a pain for that.
 

Thanks Fog.  Great suggestions.  Did them all...........no go.  I got my hopes up because I had in fact moved usb ports.  Re-installed still no luck.

Before attempting to make adjustments within Sonar, first check that audio is working ok outside of Sonar, e.g. playback from YouTube or Media Player.  If it doesn't, get it working in Windows first before doing anything with Sonar.
 

Hi Kev, that was my very first step.  Sound card is fine, works with everythnig else.

I just gave a quick play around and the most obvious thing for me to get NO meters
at all is to have something soloed. I know you've checked your tracks. Have you checked
for any extra bus that is soloed? Easy to overlook.
 
I'm not laughing....once I had headphones on and spent a few minutes wondering why
I wasn't getting sound... checking out the routing. Then I realized the headphone amp
wasn't on..... stuff happens to all of us.
 
Hope you get it figured out.

So you say the audio engine icon is lit up?

And you have reinstalled your audio device right?

If you have X2 still installed, does any project play in there?

And I agree with others that say it must be something soloed.

But you did say you tried other projects with the same results?

check your I/O's (inputs /outputs in your track view or console view, do you see meters moving ?
if so its got to be an I/O issue, 90% sure.

But he says no meters move. None.