Cubase 5 Remapping Old File settings

While i have a collection of project files from a few years back when I had Cubase 5 installed on my PC, I have since installed it on my Mac with the same VST instruments. However when I open these earlier projects, they show the Instruments as being missing. If I add the Instrument myself through the Devices > Instruments menu, they do appear but without any sounds mapped. Is there a way I can fix the mapping so the files will open with the correct mapped sounds? Or have those been lost now since I’ve reinstalled.
Do I need to move the instrument file to a specific folder? Do I need to add a new mapping setting in Plug In Information? Or do I need to remove/modify an existing one? I’ve tried a few but to no avail.
Hope someone can assist out there who may have experienced the same issue.

Many thanks
SonO :confused: fJack