I have a website, it is 2 years old. All of the main keywords are ranking around 10 position. It is not a good SEO website. In the last 1.5 month, i added about 800 blog comments. But it seems no help for the ranks. At the same time, i added a subsite at the domain with 5,000 products. Good has been indexing the new pages slowly. But yesterday, all of my main keywords lost its ranks and get out of 10 pages. I have a analysis of the google webmaster, it said all of the ranks doesn't changed. The updated date is 28 Set. But when i had a checked again now, it shows all of the ranks doesn't change. And the updated date is 29 Set. But i have a check of google, i still lost the ranks. Why? And why my ranks disappeared?