Cannot see my objects in BluePrint viewport.

Hi Guys,
I am very new to UE4 and trying to learn. I just started on unreal engine and I have following issue. I created a blueprint class and added few actors to it. Everything went well but on one day I cannot see any of my objects (at least not how they are supposed to appear) in my viewport window of blueprint class. Please see screenshot below. I may be too stupid and did something dumb but, I am not sure how to get out of this view. Rest of my blueprints are fine. I tried to zoom out and rotate the view but all I see is a blue line. I cannot see any of my objects.

Is there a message saying this is a data only blueprint? If so, click on the open full blueprint editor link

Select the CUBE in your list, and mouse over the viewport and press F - that will center the cube in your view. If its still not there, make sure its ‘visible’ on the right details panel. - good luck!