Your 1st Post - My 1 TB External HDD suddenly became Unallocated. Whenever I plug the device onto a computer a prompt pop-ups for disk initialization.
Your 5th post - I do not own the drive so I don't want to take any experiments on this.
Im somewhat now confused , is it your drive ? or someones elses ?
Either way im fairly sure a Drive that is not Initilized - cannot be accessed IMO.
So im not going to direct you in a possible fix if any backups were not done previously on that drive.
In my view when the drive is Initilized this will give access , if then anything is lost ? then a recovery program eg: Recuva , may be able to recover them.
Best bet would be to wait for an Expert within BC on hardware issues to assist you in solving this , so be patient until then to get the best outcome.