My site had pageviews of approxmately 4000/daily.Suddenly it dropped to 200/Daily.Idont know wat mistake i did. How can i recover my Google traffic
There may have recently been a new round of Google updates, perhaps someone else on the forum can confirm this?
Sounds like your site may have been affected by Google updates as Oly says. Can you recover your Google traffic - who knows. You're ultimately at the whim of Google as we all are. As a suggestion - look at other traffic generation methods and diversify a bit so as not to rely on search engines. Facebook, Twitter and social marketing in general might be something to consider to get more traffic now?
Look over the things that you do have control over. Check your on page SEO. Make sure you don't have spammy sounding phrases. Make sure you are outlinking to niche related sites. Make sure you have diverse inbound links, don't put all your eggs in one basket. Use social media, blog posts and some article posts and directories. Diversity is the key and if you can get links from sites that are an authority in your niche, then all the better.
Do you have copied content on site? Try to write unique content and submit your sitemap to google also try to get some good backlinks from high pr websites. Also join google webmaster with your website to see whats wrong with your site.
You've been Scroogled! Or Pandalized.. or, Penguinated.. Read up on Google Panda and Google Penguin and see if those changes/penalties apply to your website. If they do, make the appropriate changes and wait..
It might have happened because of Google Panda Algo Update, You can read http://www.1001tricks.com/2011/10/i-got-hit-by-panda-update-badly.html to learn some tips to recover from Panda update.