Ban term explained
The ban is off site from the search index due to the inconsistency of rules or accidental loss of the website due to the glitches of the search engine (the second is fairly rare).
The ban is usually exposed sites do not bring users to valuable content or contain duplicate content that use black optimization techniques such as hidden text or links.
To avoid ban, you need to care primarily about the site visitors and use only white methods of promotion in search engines. If your site is already banned, and you do not see the reasons, then you need to contact customer support search engines with this question. If the reasons are known, they must first eliminate and then send the website to the recapitulation in the panel for webmasters, and then wait for a response from a few days to 1-2 weeks.