I thing that my website was hit by google penguin and the traffics go down. The reason is that the lack of content (may be) I let google index only my homepage because of the website structure. (It's the tool to check other websites technologies: http://urlscanner.net/) Is there all other similar tools also were hit? How to solve this problem. Thanks.
Unfortunately,. Google Penguin hit a lot of sites hard. Keep adding quality content to your site and focus on basic SEO to improve your ranking. Good luck.
your site doesn't have any content in it. in order to rank well, you need a content rich site that is more than one page with just few lines. add some text content on the homepage and keep adding some content rich inner pages slowly. then do some link building to BOTH homepage and inner pages. you will see your ranking going up slowly