We take plagiarism very seriously - and your comment "Except one or two articles, rest I have written my posts myself" indicates that you don't.
If your account was closed for plagiarism - and if you are the user I think you are then it most certainly was - the official rule is that your account is closed and will remain so. However, the final decision is with the staff, and you can ask them to reopen it by posting a request here:
http://www.codeproject.com/suggestions.aspx[
^]
It is very unlikely to succeed - we really do not like those that steal others hard work and try to pass it off as their own.