The requested URL /index.php/ was not found on this server.

Hi - I have a site that gives the following error, "The requested URL /index.php/ was not found on this server." I cannot find the file .htaccess that many say can solve the problem. I have an index.html file in the www folder that I actually want the site to display. I have several other sites setup the same way with the same index.html and those sites work, not sure what is wrong with this one? Thanks for any help/suggestions, Woo