Is there any way by which a user can be sent a private message or is there some other way of contacting them say, via email ?
For normal users, no. You cannot directly contact the user unless they provide the information freely on their profile.
If there is an issue with another user, feel free to let any of us moderators know.
You could find one of their posts and leave an "@name" comment for them on their post. This should then appear as a notification for them next time they're on the site, but this isn't a forum or a chatroom, so that should be used sparingly.
Perhaps that could be used to invite them to the Android room on http://chat.stackexchange.com where you can actually have a real talk, and possibly swap enough contact details that you could then have a private conversation.