Is there anywhere I can download just the ShadowHighlight.plugin or can someone e-mail it to me?
I accidently deleted mine while trying to fix a problem (http://helpx.adobe.com/after-effects/kb/crash-plugin-shadow-highlight.html).
Simply reinstall the program.
That will wipe all of my plugins and I'll have to reinstall all of those again won't I?
That's a major hassle for just one file.
You should follow Mylenium's advice.
Do you have Time Machine running? If so, it's really easy to rewind the plug-ins folder back to where it exists.