Were you logged in as the Account Owner? Once logged in, at the top of the page where it says MyVerizon, hover over that and click on View All under My Device. At the top, choose the appropriate device. Under About My Device, click on My PIN and Unlocking Key (PUK), and you should get a pop-up with the info.
If that doesn't work, then you'll need to call Customer Service or visit your local Corporate Verizon store.