Huh?  It was there.  Now not.  Where did it go?
 
SOLUTION:  Edit the Registry in Win7-64, HKEY_LOCAL_MACHINE, SOFTWARE, Cakewalk Music Software, Tools Menu:
There should be a KEY there called "Plugin Manager"
Inside that Key should be 7 items (note that some are / and some are \)
(Default) - REG_SZ - (value not set)
CmdArgs - REG_SZ - /ParentWnd$ /VSTInventoryRegKey$
ExePath - REG_SZ - C:\Program Files\Cakewalk\Shared Utilities\PluginManager.exe
MenuText - REG_SZ - Cakewalk Plug-in &Manager
Modal - REG_DWORD - 0  (it will change to 0x00000000 (0) on its own)
Type - REG_SZ - Generic
 
WHY DID THIS HAPPEN - Dunno but think a regcleaner did it
 

I edited the registry per directions to add 3rd party Utilities, and the Plugin manager is now in the list and runs HOWEVER!! it says I don't have any VST plugins installed, and the VST setup buttons are greyed out. 

Same here. Plug in manager opens, but the VST configuration buttons are all greyed out. Basically I'm trying (again) to change MIDI Guitar to an instrument, rather than a plug in. This way, however, there's no way to do that. This a new problem since the last update or 2.

Are you running plugin manager from within SONAR or outside?
It has no idea what to update unless you launch it from SONAR's tools menu.
Also if the VSTScan button is grayed out it means that the registry doesn't contain a link to it - probably something external removed it from your registry like a reg cleaner or something. Please re-install the last update and it should restore that if that is the case.

Hey, Noel. Thanks for the response. I've tried it both ways. I've also uninstalled and reinstalled multiple times without success.  It has worked with this update until a couple weeks ago, then just quit. I'm unaware of any changes that might have accounted for the change.