changing Titles, target keywords in 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 ...

Not you should but you must change them as soon as possible. Though you might lose some juice it will eventually get back there while on the other hand you might never rank for those competitive words. So yeah, change back ASAP and start creating of new content when you're at it. Just keep things rolling

Any tips from power members?