External HD not accessible

Having problems w/ex hd & went on only to see that many others have the same problem.

Had ‘my passport’ ex hd for several months before it no longer would register.  Sadly, didn’t back-up files.  Files will show up on blue ray player (was trying ex hd on several devices to see if it would register).  The computer acknowledges the hd but cannot pull files up.

Please advise on how to correct this issue.  Thank you.

see it in the disk manager?