I want to know what will be happen if I copy contents / articles from some de-indexed blogs and paste them into my other high ranking blogs?
Don't you think there might be some reason that those blogs were de-indexed? maybe they were de-indexed due to duplicate content issue. Why don't you check whether the de-indexed blogs had duplicate content, if no then I can't find any reason for not using the same content on other blogs...
Most of blogs were de-indexed due to selling lot of external links even they have high quality articles. Should I copy those high quality articles for my blog?
It is good if that content not indexed by Google. You can copy that and paste in your Blog. But please check that content before paste so it will not harm your blog.
If there was not any duplicate content issue, I can't find a reason why not to use your content from old blogs... Best luck