Thank you for taking the time to read my plea for help and responding.
Yes I tried going back to the original prog. and maps etc. that I backed up from the installation when I bought the multimedia system.
My concern is that I am missing something like a piece of software or that there is a problem with copying the files / folders to the SD card as per the note in the user manual.("Please copy the navigation map software to the system storage memory (presumably the SD card) first, and then install the navigation APK.") It is not clear whether the zip folder should be unzipped first or copied as is.
When I took the unzipped method the error showed that it could not find a "zip archive". When copied as a zip folder, it asked for the SD card to be inserted. Very puzzling.