Either he is not there on the other end of the email, or does not wish to be contacted. Except for a brief interlude around the time of the takeover, the owners and admins of the site have been unobtrusive.
If you want to comment on an article, there is space provided at the end of every article.
If you want to contact somebody about writing an article, click the link for "write for us" that appears on every page and you will see further information and an address. If you have already seen that link and that is what you have already used and referenced ("I have contacted him/her already but no reply."), AND an appropriate amount of time has passed (IOW give folks more than a day or two), you could, politely send it again.