Site listings disappeared

I have had great listing in Google for a few of our important keywords
for a few years now - now our listing have just about disappeared.

At this point we are at a complete loss as to why and how it can be
fixed.

Regards

Original article from http://groups.google.com/group/Google_Webmaster_Help-Indexing/browse_thread/thread/ec1f76994f8c5825/3fb381e7aadec3c8?show_docid=3fb381e7aadec3c8