Thanks Neme & lujuris.
I have ordered a second memory card which should be getting delivered today so I can test it against the card I have now and report back once I have.
If that fails I'll have another try at tinkering with all the bits and bytes again thanks lujuris for digging out the Pal string! :)
I'm slowly filling up my so-called 'cannot be found' memory card which is the main thing that's bothering me. I hope this new card fixes that!