Just check how your site is performing in Google analytics. If your search engine traffic has been decreased, that means your site keywords have dropped rankings. Build the high quality links and remove the low quality links for your website.
1. Sudden Google referral traffic drop 2. Huge differences in rankings if you query general search and a single database. 3 Your domain is not #1 for [yourdomain.com] search. 4. [site:yourdomain.com] returns 0 results
When you find that you lost your ranking and the traffic is dropped tremendously, you can be sure that you are affected, A lot of tips are available, but I am still searching something that can help to regain the previous PR.
ummm, probably when your rankings and traffic go down... Hard to tell you how to fix it when we don't know why it was penalized, if it was. maybe if you post your site we can review it and give suggestions.
Your website results in the google goes to last results (your website/pages ranking will fall down). You will see the decrease in the website traffic.