Post-Maverick upgrade, now my firewire MyBook does not mount

This external firewire MyBook worked fine and continues to work fine if I boot up Snow Leopard.  However, if I boot up into Mavericks then the MyBook will not mount nor become visible in Disk Utility.  I am not running nor have ever run any WD software and so it is not related to that issue.

TIA

Mavericks caution, upgrade your WD Drive Manager to the latest version available. 

http://community.wd.com/t5/External-Drives-for-Mac/External-Drives-for-Mac-Experiencing-Data-Loss-with-Maverick-OS/td-p/613775

I hope that is only formatting issue … and that is not an old version of WD drive manager have deleted your data :cry:

in case of problems on mac OS format (when Disk Utility does not work properly), can be solved using DiskWarrior.  http://www.alsoft.com/diskwarrior/