I formatted the wrong device (a TrueCrypt encrypted NTFS HDD) using TransMac (
http://www.acutesystems.com/scrtm.htm). I realized it within seconds and plugged out the USB connection of the device immediately. Needless to say, I can't mount the device with TrueCrypt anymore .
So I tried TestDisk. I ran the Deeper Search analysis and this is what I got:
What I am supposed to do next? Pressing p on the entries did nothing but telling me: "Support for this filesystem hasn't been implemented".