My Book Locked and Can't be Accessed

WD External Drives External Drives for Mac
1

I’m using a 1TB My Book for Mac… on a iMac running OS X 10.5. However, I left my machine came back and there was a padlock icon added to the My Book desktop icon. When I try to access it… I’m being told that I don’t have sufficient privileges.

How do I get to access the drive again?