NTFS drive is not mounted after changing /etc/fstab
Generally the mount command is not used under the OS X operating system. Apple has there own command called diskutil. This basically the command line version of the Disk Utility application. The command line version has more functionality than the UI version. If an external drive is recognized by OS X, it will show up under diskutil list as /dev/diskX were X is a positive integer. To mount a drive enter the following command.

diskutil mountDisk /dev/diskX


To unmount use the following.

diskutil unmountDisk /dev/diskX


Partition Y on disk X is denoted as /dev/disk/XsY as shown in diskutil list. To mount and unmount a partition use the following.

diskutil mount /dev/diskXsY
diskutil unmount /dev/diskXsY


The mount command can used to see if a partition is currently mounted. Just enter the command without any options.

Be default NTFS partitions are mounted as read only. I guess there is a way to mount without the protection of read only status, but from what I have read this is unsafe. 

Companies such as Paragon offer software that allows OS X to write to NTFS volumes. I have never used such software.