Can you bring a hard drive back to life if won't mount in finder?? Yes we can Bob.
Forget diskutil, forget Diskwarrior. Find Testdisk and download it.
Double the program to run in terminal. After sticking SUDO password.
Set it loose on the Drive and tell it it's an Mac volume.
It will report a partition and size like:
HFS 263968 268433209 268169242 [wickert family 2]