You can't hack Hitachi drives so you need an undo.bin for what ever Western Digital hard drive you hacked.
Look on your actual hard drive and see what make / model it is, then see if someone has uploaded an undo.bin for the actual hard drive.
That is not a hard drive you have hacked, it's a hard drive that has come in an Xbox 360 so no undo.bin will exist for it. Hddhackr only works with Western Digital hard drives.