Many times, you'll see an interesting blog, and want to contact the owner.
In other cases, you'll be unable to even see the blog, because it's private. Or maybe a popular blog, that you're used to seeing, has been deleted, or is now private. Or maybe you want to use a given URL, but that URL is already in use. How do you contact the owner then?
In other cases, maybe somebody has left comments on your blog, you want to read his blog, but he's not providing any link. And, his profile doesn't show any published blogs. Can you figure out if he's actually published any?
The most popular means of contact, with an unknown blog owner, is comments.
Commenting is a native feature in Blogger, and there are third party products too. But both the native Blogger comments, and the third party ones, are optional, some blogs don't use either, and sometimes the comments that you leave don't get read, or are ignored.
So, what do you do if comments don't produce results? Or, if you don't have a blog to comment on?
Blogger will not help you violate the privacy of the owner.
Don't waste time asking Blogger for help. Blogger protects the privacy of bloggers, and they won't provide contact information.
If a blog is setup as private, the owner wants people to be able to request access, and he really thinks about what he's doing, he'll make it possible to be contacted. If there's no information in the profile, Blogger won't help you.
You can, if you wish, look for a contact point.
But what if the owner didn't make it possible to be contacted, at least by a published email address, or a listed blog? If he's not a complete recluse, chances are that he's left a trail, somewhere, on the web.
For a Blogger Blog, you can start with Google Blog Search. GBS will search for a Blogger Blog, and give you information relevant to Blogger Blogs, that you won't find in a general web search.
Next, go to Google Web Search, and some other web searches (and there are no end to the possibilities here). Plug in the URL of the blog, or the profile of the blogger.
See if any posts, or web site entries, show up for that URL, or profile. It's likely that somewhere, one or two posts, or web site entries may be from him, or from third parties who know how to contact him. Maybe he left an email address somewhere.
If he posted in a forum somewhere, maybe a private forum message will reach him.
In some forums, forum members can send private messages to folks who post there. You may not get the email address you want, immediately, but if someone is a forum member, maybe you can send email blindly.
If a blog owner, as a forum member, feels moved to respond, so much the better. And if you become active in a relevant forum where he's a member, maybe you can communicate with him there.
Or, if you find an existing, semi-current, thread where he has already posted, you may be able to weave an answer to one of his posts into that thread, with your own thoughts. Try and make your post as topical as possible, though.
Here, research is your friend.
Good old fashioned detective work and diplomacy. It's still applicable. Google may be a friend, but it's not your only friend. Think about it.
And if the owner is willing to give up the URL, have it transferred properly. Please do not have it transferred by deletion.
An Important Update
If you did not use a Blogger / Google account when you Followed this blog, years ago, you are probably not Following now . During the past...