I ran into an issue while working on the road one day. Normally, whether I am working in the office or at home, I have a second monitor hooked up to my laptop. This can sometimes pose an issue when you switch to a single monitor as some windows or dialogs will not recognize that the second monitor has been removed and they will be invisible to you as they are not rendering on the screen. This is likely what triggered my issue in SQL Server, one that was not resolved when I hooked up my second monitor again the next day. In order to recover my missing Find dialog I had to reset the window layout by following the bellow steps:
After that my Find dialog displayed as expected. I had a few new panes open that I was used to seeing but I quickly closed them as I rarely use them.