The drive may have failed. To find out if it has, test it with SeaTools for Windows: http://www.seagate.com/gb/en/support/downloads/seatools/seatools-win-master/
I hope you copied the data from it to another location when it was working okay.
The drive may have failed. To find out if it has, test it with SeaTools for Windows: http://www.seagate.com/gb/en/support/downloads/seatools/seatools-win-master/
I hope you copied the data from it to another location when it was working okay.