The EZkeys.dii and EZdrummer.dll are in the following folder: program files---cakewalk---vstplugins---toontrack.
Also they are nowhere to be found in: program files(X86)---cakewalk---vst plugins.
All this problem is on my Dell computer. On this computer I have also had to remove and reinstall Sonar a couple of times in the last 8/9 months. I am starting to wonder if the Dell computer is not the issue.
I also have an HP laptop that I originally used for my music. Nothing of this sort has ever happened.   All the toontrack are in their proper files and work perfectly.
I am at a loss. I like the Dell because of the much bigger screen but if it going to keep acting up, I guess I will have to go back to the smaller screen laptop.
 Thanks.

Although a reinstall of EzDrummer and EZKeys should not be required as others have said, perhaps it could cure your ills?

I did a reinstall of EZdrummer only, but to no avail. Maybe if I do both EZdrummer and EZkeys that could solve the issue.
I will try tomorrow and see.
If I have a problem I will be back.....
 
Thanks again.

I don't think that would help, but . . .
 
I'm just firing up X3 to have a look to check something, haven't fired it up in years

And you tried a rescan (rescan failed plug ins) ?

and perhaps a reset first

Also do you have another DAW, and does EZd and EZk work within it? If you don't you could download REAPER Demo, it's only around 11MB download and has a small footprint (also doesn't expire and is fully functional) you could install it and point it to your VST folder where you have EZd and EZk (Options - Preferences - VST and set the Path there), scan and see if they work from within REAPER, if they do then you could probably rule out problems with the plugs themselves. If you choose to test with REAPER, you can select the 'Portable install' option on installation and that keeps everything self contained in the one folder so everything is neat and tidy, and if you want to get rid of it after you have finished testing you just have the one folder to simply delete.

Thank you everyone for your inputs.
Solved the problem by comparing my laptop and Dell files. It seems that when the problem occurred the Toontrack plug-ins that were in the PROGRAM FILES (x86) of the Dell computer got erased for one reason or other.
By re-installing in the proper file everything now seems to be working fine.
However I still cannot understand why the Dell is giving me so much  problems when it come to Sonar X3. In the past year I have had to re-install Sonar a few times. But all is fine on my HP laptop: no issues in the last 2/3 years.
???????
 
Thank you again to all.