Forum Moderators: mack
your experiences, views , opinions are most welcome
black hat seo techniques, links to and from wrong or unrelated sites, spam attempts from your domain name etc etc..
Or maybe your rivals have used black hat techniques to give them a quick rise in the rankings...or maybe they've used white hat techniques recently, either themselves or hiring an seo company and have had a surge in the rankings.
Theres alot of factors
:)
There are too many factors that could lead to your site dropping like that and without knowing the history of your site and all changes made to it, it can be difficult to tell what is going on.
Set yourself up on Google's Webmaster Tools and submit your Google sitemap (if you are not already doing this). That is pretty simple to do and can be used as a good starting point.