No Space detected on Hard drive

Do not do anything with this HD anymore -- until you have posted a similar thread over in hddguru's conventional hard-drive forum. There are numerous hardware and software level data recovery folks ranging from newbie to professional. Admit that you are now asking for their advice, perhaps even linking to this thread. I have no experience with GPT setup, so I am useless here.
There exists also data-medics forum and recovery force forums -- however, they may lean towards having you send that HD to a data recovery company/specialist; and if you are not leaning that way at this time, consider hddguru forum as the second place to visit.
If jumanji enters this thread -- follow his advice to the letter! :)

Is this your Buffalo drive 1TB HD-PCF1.0U3BB http://www.buffalo-technology.com/pr...le-hard-drive/
Datasheet http://www.buffalo-technology.com/up...rive_EN_02.pdf

In all probability the SATA to USB bridge electronics inside the enclosure has failed. That is why it is not even showing the capacity. The HDD inside the enclosure may be OK and the data can be recovered. Unfortunately it is not a DIY project for the simple reason the manufacturer might have soldered the bridge Electronics directly to the HDD to make it compact. ( The HDD may not have the usual SATA connector) So it is not possible to take the HDD out and connect it directly to the motherboard to retrieve the data.

Please discuss the issue with Buffalo Tech Support and find out whether they can help replace the bridge PCB and recover the data or will they recommend any professional data recovery agency for Buffalo HDDs who can do it.

Just for the record and perhaps a 1% chance recovery possible, post a Windows Disk Management screenshot again. But this time try to initialise it as MBR and not GPT(as you had done). Post the error message if any. If initialisation goes through just stop with initialisation and do not proceed further to create a new volume and format it. (Initialisation only writes the MBR code to Sector 0 and does not affect any data in other sectors)

Uninstall the latest version of Partition Wizard and install v9.1 which can be downloaded from http://www.filehorse.com/download-pa.../old-versions/
Post a screenshot of how your Buffalo drive appears in it.

If there is a chance of recovery, we shall proceed with this version of PW.( Not free in later versions)

EDIT: Also try with a new/different cable to exclude the possibility of a faulty cable.Try on another PC as well.