The conversion was a disaster.

Could that be of anything to do with the partition table or something?

Im pretty sure the partition wouldn't pop up just by using some partition software or so; I attempted partition magic, the lost partition was displayed empty.

I used the Windows Disk Management, again it was empty. I had attempted to recover the files with both getdataback for ntfs and fat, and it failed, with the error message:

Error 65284 reading partition (sector 304592400) of drive 'HD128:'(FSIFC:343) 00490774
I do really appreciate your patience and help, however the files are really important, and am totally no clue of what has gone wrong. Thanks again and in advance for your assistance.