I see that you need the drivers for the Laserjet 1020 plus for Yosemite. I would like to help you.
The Laserjet 1020 plus printer is only supported on a Windows computer. There are no drivers available for any Mac operating system. Here is the website showing the available drivers. HP LaserJet 1020 Plus Printer.
You can check to see if Apple has a compatible driver. This document provides the steps for running the Apple Updates.