I was creating track templates yesterday, until I think Sonar thought I was going too fast, then it crashed.
I opened it back up, no sound.  I went into the audio settings, it showed everthing like it usually does, but in parenthesis is showed (inactvated).
 
I've never had this problem in the past 4 years.  The UX1 is my only sound card setting, iTunes played fine through it right afterwards, so did POD Farm, just not Sonar.
 
Any insight as to what may be causing this?

It's common for Sonar to loose contact with the drivers for various reasons. Just re boot your interface with Sonar open and Sonar will re connect. 

I've re-started the computer twice, once last night, and once this morning.

Still silent.  Perhaps I'll check for driver updates with Line 6.

I said re boot your interface,, not the computer. 

If the interface is working with other applications then re booting your computer will change nothing. Sonar just lost it's connection. With Sonar open,,,Turn off your interface, wait 30 seconds, and then turn it on again. 

If the interface doesn't have a power switch then unplug it from the USB port. 
Always use the same USB port too. 

Is the USX1 showing in the Audio options / Drivers as the "Checked" device? 

I'll try this when I get home.
So, just so I understand this correctly.
 
Should I leave the computer on, then unplug the USB cable to the interface, wait a minute, then re-plug in?
 
Should Sonar be on/off while I do this?

Problem solved.

Lemme 'splain.

I feel really stupit, but I think what happened when I was working fast and Sonar crashed is that somehow the master fader strip had the output switched.  

I tried unplugging the interface, wait, re-plug & all that.  Then I felt directed to open up another song file.  I examined all of the strip(s) settings, and when I went back into the troublesome file, noticed where the anomaly was.

Thanks for all your help guys.  Also, I created track templates for every single soft synth in my list.  I recently got the Arturia Analog Experience Laboratory 49, and that was the first one I set up.  I didn't realize just how many nice synths come with Sonar, as I only dabbled in the Groove Synth to a small degree (don't like its minimal adjustability) and the PSYNN II, which I think is great.  The Arturia is still my "go to" pick for analog stuff, but nice to know there's other stuff in my tool box.  The Pure Piano is nice along with the TSS-1, and for other sample based stuff, orchestral & stuff, I use the E-MU Proteus VX which was a free download from their site a few years back.

 it showed everthing like it usually does, but in parenthesis is showed (inactvated). 


This was a mystery to me. Where exactly did you see this? 
I almost always advice people to check the Master output but you made the above statement so I would not come to that conclusion.

 I just set my Master output to "none" and I don't see any "inactivated" anywhere in the Audio options??. I don't think this information was correct. 

Should I leave the computer on, then unplug the USB cable to the interface, wait a minute, then re-plug in?    

With Sonar open,,,Turn off your interface, wait 30 seconds, and then turn it on again.  

Line 6 Audio/Midi devices.
In this thread, it's like the pic shown, and right above where the circle is "Driver Operating at.....", that's where (Inactivate) appeared.
http://line6.com/support/thread/38598
 
I think it was just a one time anomally, never has happened before.  I think it happened in error as part of the dropout.