Google Inc.’s mysterious methods for ranking Web sites came under attack Friday in a lawsuit accusing the online search engine leader of ruining scores of Internet businesses that have been wrongfully banished from its index.

The civil complaint, filed in U.S. District Court in San Jose, Calif., by KinderStart.com, seeks to be certified as a class action representing the owners of all Web sites blacklisted by Google’s Internet-leading search engine since January 2001.