How do I retrieve sticky notes that whisked up and away ?

Open Stickies. In the Dock, right click on the Stickies icon and select Show All Windows. Have the Stickies reappeared?

In the Stickies App, select Window => Bring All to Front

Do either of these resolve the issue?

Glad that worked. The same thing happened to my wife when we got her a new Mac and migrated everything from the old Mac. She was very unhappy not being able to see all her Stickies and I was in big trouble until I figured out how to get them back! I am pleased yours are back too!