Been a bit busy these past few days so I couldn't help :(
I think that I understand your layout...............you have a laptop with its own HDD which is bootable and contains your OS. Your personal data are stored on an external (USB connection) that you have not defined as bootable? Effectively it is like a slave drive to a desktop?
"Fixboot" won't work because the drive isn't bootable ;)
"Fixmbr" might work (I have never tried in this particular situation) because it will find the backup record that is hidden on the drive and reinstall it:)
Your problem is that your Master File Table (MFT) was deleted. This contains metadata that defines an NTFS volume, and is a part of the MBR.
A recovery application such as you mentioned should work, as should the various bootable disks mentioned (remember to go into BIOS and allow them to boot ;)).
So, why am I posting this crap guys?
Well, there is this App I have been using for years........it works, and it is free, and there are Windoze and Linux versions.
This is pretty much an avenue of last resort, as it takes a long time to run, and requires a drive or partition of at least equal size to the one to be recovered.
It doesn't care about your MBR or whatever, as it works at a very low level, scanning your drive and re-assembling files. It will even re-assemble damaged files as best it can, and work on damaged drives, so long as they can spin.
It has never let me down, although I haven't had to use it a lot (thank God!)