bobby@bobby-ubuntu:~$ sudo mount /dev/sda4
NTFS signature is missing.
Failed to startup volume: Invalid argument
Failed to mount '/dev/sda4': Invalid argument
The device '/dev/sda4' doesn't have a valid NTFS.
Maybe you selected the wrong device? Or the whole disk instead of a
partition (e.g. /dev/hda, not /dev/hda1)? Or the other way around?
bobby@bobby-ubuntu:~$