the disk you inserted was not readable by this computer.

i have a macbook pro, my hardrive is about 2 months old (seagate Backup Plus Hard drive, 1TB). plugged it inot my blueray dvd player to watch something and the only way i could watch it was if the player converted it or somthing to a HDD thingy. i plugged it back into my mac and it popped up with this message:

The disk you inserted was not readable by this computer - options: initialize, ignore or eject

im not sure how to get it working without deleting all its content!! PLEASE HELP MEEEE XOXOXO