Last week, all my posts are in the first page of google search by searching the appropriate keywords. Just days ago, everthing I post is not being indexed by Google. But my previous posts still exists in the first page. Can somebody explain to me what happened?
keep ur posts original and keep pinging google and also various web directories so that google crawls u better
Sign up and use Google Webmaster Tools. Make sure you have a Google compliant xml sitemap to submit. Once you sign up for webmaster tools, set up your website/s on there, and use Google Analytics on your site, you will have a much better understanding of what is going on with your site, and exactly what pages are indexed and which are not, possible reasons why, etc... I highly recommend using this if you plan on getting a good amount of traffic from Google and making money with ads and affiliate programs. Hope this helps
If you're using wordpress, install a sitemap plugin. The best one is in the Top 5 at Wordpress Extend.
I did this already. I just added ..atom.xml, or something link that in the link I added, is that correct?