Thank You for such a nice and descriptive answer, you're 100% right and I did not received any manual penalty from Google. I even tried to add up new content but it does not made any difference so I thought to transfer all the content to new domain. By the way you've got semrush premium account? and how much useful is that?

And one thing more, almost 2 weeks ago, I also changed the permalink structure which encountered in so many 404s but then I manually edited all the links and made some redirection changes to my .htaccess file.

Hey Philip thanks for your response, My domain is ohguideme.com, over the recent months i have made so many changes to its look and almost have edited many posts and even deleted some of the poor posts that I thought were of poor quality but then there is still no improvement in rankings. I even paid a guy who was boasting that he will recover my site but nothing happened. Do you have any suggestions or tips? What should i do with it???

Well I still don't know why was my site hit by Humming Bird update and it was in Mid-August, My site content was original but I guess it was due to poor internal backlinks.. So what should I do now? Delete my existing domain and transfer all the posts??

Hey Moz experts, I had a domain which was really doing better but after the Humming Bird update my traffic was decreased up to 90%. There are plenty of posts on my existing blog, Now what should I do? I mean should I redirect it to a brand new domain or Copy all the posts to a brand new domain and delete my existing domain? Note that the Old domain has PR1, DA 19 and PA 30.