changing Titles, target keywords all all articles.

I messed up by targeting competitive keywords and now the site has frozen on its position. Its earning nothing. Earlier I was targeting long tail keywords and it used to rank well but I got greedy and changed my target URLs and titles in all articles ...

Would it be a good idea if change the titles and main keywords in articles, metas back to long tail medium search keywords with low competition like earlier...?

Even if that doesnot work then I would de-index this entire site and start new one with same content targeting long tail keywords ...

Suddenly changing everything all at once may be a bad idea. When I want to change keyword density or targeting I do it a little at a time over a few weeks or a few months depending on size and index speed. Also I don't go back and change articles. I just publish new ones. The metas and main page content is what I morph slowly. Google isn't retarded, they know if you suddenly change articles and metas and main pages to target a new keyword.

-ThopHayt