Seagate Backup Plus HDD Problem

Suddenly My external Seagate Backup Plus is not showing on my iMac Mid 2011 version, listed below is that the fundamental facts about my drive

- Storage Size : 2 TB

- File System : NTFS

- The drive is using power supply and USB wire.

I have tried to unmount and mount the drive, but it still not functioning as used to be. I have used paragon ntfs for mac to mount and no success, it give a message the volume is marked as dirty.

Any help please, the HDD is full of precious data