Mybook Studio suddenly can't access on my IMAC

WD External Drives External Drives for Mac
2

Hi, check if you are using password protection for the my book. You can also open the disk utility window and verify if it’s recognized there. 

http://wdc.custhelp.com/app/answers/detail/a_id/866/session/L3RpbWUvMTM1NDczODUwOS9zaWQvSWxua0lfY2w%3D