When you shut down your system ALL filesystems were unmounted as part of the shutdown process, including the FAT32 partition. You lost partition information is not the result of Linux shutting down, you did make a newbie mistake however, Microsoft filesystems do not understand or care about Linux permissions at all (the chmod 777 bit).
To answer your question, restore from backup. You do not have one then lesson learned.
I would suggest that you take the time and truly fix your partitions issue and learn how to properly mount FAT32 partitions for use by non-root users in Linux.