Msg 39011 SQL Server was unable to communicate with the LaunchPad service
In order to move TempDB to a disk with more space, I had to restart the server.
This stopped the SQL Server as well as SQL Agent, and the new "SQL Server Launchpad".

It was easy to restart SQL Server and SQL Agent. 
To restart LaunchPad, I needed to go to 

Administrative Tools -> Services 
and find "SQL Server LaunchPad (MSSQLSERVER)"

right-click it and select "Start"
and my scripts run again.