64mb memory deleted everything and it won't show up anymore
Well in that case its deleted.
If it was REALLY important, there is (expensive) software out there that recovers lost data, I mainly hear of it being used on hard drives. Would probably work on a memory card if you can connect it to your computer.
I don't know any software names or brands to help though, sorry.
you can't retrieve it once it's erased..you'll just have to start over.
for future refrence,dont turn off your console mid-save or open your disc tray..thats what causes fragmented or corrupted data on a memory unit.
what memory card are you on about? a phone one? obviously if you delete everything the contents wont show.