I think the problem could be one of two things. In your question, you say "return back to the ViewController", but you are not going back to the one you started with, you're creating a new one. If you got to the detail controller by pushing from ViewController in a storyboard, then this is not the way to do it. You need to get a reference to the original instance of ViewController, or use a protocol (which is the standard way Apple recommends for sending data back to a controller). There are several ways to get that reference, you could have a property in the detail controller called mainController, say, and ViewController could set itself as the value of that property when it pushes the detail controller.
Another possible problem is a simple one -- the table is using a plain cell rather than the one that has the detailTextLabel. Make sure you've set the right kind of cell in IB.