Here are some question that you might figure out: Does your site ranks on SERP? Do you have quality backlinks to support you rankings? Is you site content and structure SEO friendly? How do you promote your site? Have you try Link Baiting to obtain quality back links?
When you check your site traffic statistics for where visitors are coming from and in what numbers, for which keyword searches and from which search engines, you will be astonished to see that things you think are important are sometimes not so important.
Thank you for your responses guys, the site is restored now, it seems the datacenters are being updated so, if you experienced the same issue don't be panic.
nice!! You also try to find the new ways to how to get more traffic. And, those visitors may be converted into customers.
get other way to bring traffic like seo gujarat said, then increase your back link from authority site.
If you are registered in google webmasters tools and use a sitemap: http://www.google.com/webmasters (webmasters tools - statistics), you should take a look at the keywords that have generated your traffic from google in the past and try to make new searches with those same keywords to see if your present results rank the same positions. Maybe for some reason, you got down in the classification pages, by losing PR, or simply because the web is constantly evolving...