Lost VST Sounds

I am running Sonar Pro on Win7. It has been working beautifully until I let my grandkids have a 'play' with my midi keyboard. As kids will, they pushed every button on the keyboard. That's not usually a problem. But, now, when I load a VST instrument, no instruments are loaded with it. For example, when loading Real Guitar, a message on the interface says 'guitars not found'. I have rescanned all VST's but still no luck. If I load a project created prior to the kids intervention, I can still get sounds out of the VST's in that project. If starting a new project and loading the same VSTs, no sound! Sonar still receives midi signals as I can see the meters rise and fall when playing the VST. Also, when playing a General Midi instrument, the output sound works as it should. I am stumped and would appreciate any advice (except advice about not letting grandchildren loose on a midi keyboard!)  

Thanks Ken. Yes, I tried the reset of the keyboard and also struggle to see a relationship between the keyboard and VSTi's. I uninstalled Real Guitar and re-installed it but the same problem arises - no sounds. Sounds do happen in that VSTi if I load an old project that used the VSTi. I can even use the keyboard to record extra chords into the existing track. But, if trying to add another iteration of Real Guitar - no sounds! I'm lost with this one!

Ruckman65
.... I have rescanned all VST's but still no luck...

Did you reset plugs first before the rescan?  It's been known to make a difference.

At a loss for anything I can think of I toss out this.. MIDI channel? 
DO you use omni? of channel 1. They might have reset the keyboard to send on a different channel? 
 
But you saying the VST shows there's no instrument loaded at all? and none are available from the load instument menu? Did you ever creat a custom pre set? 
 

What happens if you load an old project, and try to add a new VST instrument?  If it plays back okay, then that would suggest your problem is the template for new projects  (Normal, or whatever you use) is corrupted.
 
Also, try deleting aud.ini and let it get recreated.

The only relationship I can imagine behind a keyboard command and a change in the behavior of softsynths would be if some kind of bank/patch change was sent. So your synths are looking for instruments in the wrong bank. If your keyboard has bank selection buttons or controls that can be mapped to that function I would look there.

JohnD - When loading an old project and adding a new VSTi, the new VSTi does not play back. I can add a recording to the existing VSTi.
Slartabartfast - I would have thought doing a factory reset would have corrected any issues with bank change/patch change info, although your suggestion is quite logical.  
Ken - I have checked a new installation of Real Guitar on another PC and it works fine. 
So, still at a loss. I am considering a complete re-intsall of Sonar and all VSTi's, as painful as that would be but I have this nagging thought that the problem could still exist after that because the issue may be hardware based rather than software based.
Thank you all for your great suggestions so far. 

Thank you for the advice. I will give that a shot today and see how that goes. I did try re-installing a couple of the VSTi's but, as you suggest, it did not make a difference. 

JohnD - I tried your suggestion of taking the HW keyboard out of the equation and using a virtual keyboard but the problem persists.
 
Mike, there is activity in the channel meters for both audio and midi. The signal routed through my Sound Canvas module triggers midi and I can hear all midi sounds. The problem is with the VSTi's. Midi activity is shown and the channel meters register the signal but there is no sound! 

Thank you for the advice, Albert. I have checked that but that does not appear to be the problem. Good luck with your Kontakt player issue.

Ruckman65
JohnD - I tried your suggestion of taking the HW keyboard out of the equation and using a virtual keyboard but the problem persists.
 
Mike, there is activity in the channel meters for both audio and midi. The signal routed through my Sound Canvas module triggers midi and I can hear all midi sounds. The problem is with the VSTi's. Midi activity is shown and the channel meters register the signal but there is no sound! 

This sounds more & more like a routing problem, especially if you see audio  being triggered.
 
Are the vsti tracks routed to busses? could you describe your bus structure

Bristol_Jonesey - It certainly does sound like a routing problem, I agree, but, on the surface, everything looks the same as it did prior to the problem. If I look at the routing of older projects, they look the same as those in a newly created project. The difference is, the VSTi's work in the older projects but no the new ones.The VSTi's are not routed to busses.
Slartabartfast - I have been using MidiOx to see what is happening and all appears to be OK. The events it reports match up to what ever it is I am inputting on the keyboard. The issue applies to every VSTi that I have so it appears to be a global issue rather than VSTi specific. I do not use templates to start new projects.  

Glad you are up and running again 
To bad we did not get to the bottom of it without a full system installation (could have been useful knowledge).
Best of luck.