I formatted an external hard drive from NTFS to HFS using Disk Utility in Snow Leopard. It all went fine, I loaded some files (this is a media player for television and that was that. This media player has the ability to move files and folders around itself, so I made the mistake of moving all hidden files ( /.DocumentRevisions-V100/, /.fseventsd/, /.Spotlight-V100/, /.TemporaryItems/ etc. to another folder.
After trying to mount the drive on my macbook again it would not show up. I tried to put the hidden files back in the same place I got them but no luck. One thing I noticed is that somehow I had two /.Spotlight-V100/ folders, I know there should be only one and have tried mounting with either in the right location.