I guess they didn't expect people to randomly delete core program components. I would still expect a reinstall to work though, did you check manually if the file is there? I'm not sure if the plug-in manager remembers that you removed it or something. Maybe someone knows a way to reset it? Is that also in aud.ini?

I think Sanderxpander is correct in suggesting the Aud.ini file (let Sonar rebuild it).
If you uninstall Sonar when there is a similar problem like this, you have to make sure its a clean uninstall
(getting all components/except presets and saved layouts, exc).
 
We have all done things like this in our lives. Once I installed a program that associated all my files with this program. I was too inexperienced to know what was going on so I had to reformat my whole HD. Took me hours (didn't have a back). So lesson learned, its all good. A back up wont take long.
 
Good luck man
 
PS- And stay away from core components
 

"A back up wont take long."
Yes, you are absolutely right.
I have a very new system partition backup, because I recently replaced the whole system (new mainboard and CPU).
The backup took nearly 30 minutes.
The system change was the occasion for me, to remove my obsolete plugins.
I didn't know, that this plugin was essential for Sonar.
The partition recovery is the best solution I think.