I have used a 64GB TransFlash cars from SanDisk for over 1,5 years and now, after I wrote a large WAV file to it, it started to behave in a strange way:
all the files and folders on it are readable. If I write something to it or even delete a partition it pretends that operations were done successfully, but on next re-read or next card re-mount it turns out that the complete old state has been kept intact, no changes were made.
Is the card damaged permanently?