Have you checked with WD for any upgrades to the software? If there isn't any and you have been using that software to backup your computer, then you will need to repartition the drive (erases all the data on the drive) and reformat it. You may then start new backups using Time Machine or other backup software.
Basic Backup
For some people Time Machine will be more than adequate. Time Machine is part of OS X. There are three components:
1. A Time Machine preferences panel as part of System Preferences;
2. A Time Machine application located in the Applications folder. It is
used to manage backups and to restore backups. Time Machine
requires a backup drive that is at least twice the capacity of the
drive being backed up.
3. Time Machine requires a backup drive that is at least double the
capacity of the drive(s) it backs up.
Other Suggested Backup Software
1. Carbon Copy Cloner
2. Get Backup
3. Deja Vu
4. SuperDuper!
5. Synk Pro
6. Tri-Backup
Others may be found at MacUpdate.
Visit The XLab FAQs and read the FAQ on backup and restore. Also read How to Back Up and Restore Your Files.