Banned

When a site that used to be included inside the search engine index is suddenly removed from this index they might have been banned. Most of the time a search engine ban is caused by stepping over the guidelines set the search engine in question.

The usage of black hat seo techniques can be one of the reasons for this ban. But sometimes a site is accidentally banned by the search engine. In any case, it is now possible if one is banned from the Google index to request to be re indexed. All you need to do is mend your ways, apply for a Google webmaster account and ask for forgiveness. This is done by clicking on the request to be re indexed link in the Google webmaster tools page.

It might take some time for them to respond but be patient, you will get an email telling you what to do and why you were banned form the Google index.