This method has worked for me for over three weeks now, and hasn't failed once. Perhaps this will help my fellow Parallels users and give Parallels developers a clue as to where this pesky little bug is hiding. It has appeared every time for me with the much coveted 'Search' box

Navigate away from the Start menu that has appeared.

As we all know, Windows Start menus are almost useless to those of us who do extensive administrative tasks on our domain every day, so this isn't very useful, so go on to step three.

What this will do is make the Windows Start Menu appear on one of my monitors, but the 'Search' box of the Windows doesn't appear. The Windows 10 taskbar sits at the bottom of the screen giving the user access to the Start Menu, as well as the icons of frequently used applications.

Right click on the Windows 10 VM in the task bar.

Here's what has worked every time since I've been doing it (when the Start menu becomes unresponsive): I seem to have found a consistent recovery mode when the start menu just won't appear. (For those who the start menu does not respond with right click, right click on taskbar - click on Task Manager - from File menu on the left upper corner select Run new task). 1- Right click on start menu and click on Run. I've been experimenting with the 'start' menu of Windows 10 not showing up when clicking on the virtual machine icon in the task bar with Parallels 13. Found a fix that worked for me, from user 'Funbit' in the comments of this article (the actual article is useless, the solution is in the comments).

Task bar not working in windows 10