Synths disabled in project after vst reinstated

OK, I just had a major hastle with with Native Instruments Drum Lab that runs in contact. It crashed the Sonar project so badly that after I narrowed it down to Drum Lab, I was unable to even delete it without Sonar crashing. So in the end I had to go into my vst directory and rename all versions of Kontakt 5 so they would not load when I launched the project - I couldn't find another way to do it.
 
So I launched Sonar, and it prompted me that plugins were missing, and that next time I loaded the project where the plugins were available they would be in the project again. Well, after I deleted the offending track and synth and renamed the Kontact VSTs back, I relaunched the project and everything was there. I could click on a track and Kontakt would load etc, but no sound. So I looked in the rack and my remaining instances of Kontakt are all greyed out and are silent! Kontakt loads just fine, but Sonar doesn't see to know it's there. How can I fix this?