Installing 5.4.3 requires 5.4.2 to be installed before . Cannot find 5.4.2

I am trying to install version 5.4.3. But when I try to install I get message about installing 5.4.2 as a pre-requisite.
I can't see from my control panel how I can install a 5.4.2 Launcher ? Can you point me in the right direction