Hello again guys, my wonderful

New clutch fitted mid January all okay. Leaving for work the other morning 0500 and the rear o/s wheel seized solid, tried stripping it down today, surprise couldn't get the drum off

1. What is the most likely cause!
2. Any "drum" pictorial guides around can only find "disc". I really do far better with a picture

As always fellas any words of experience and advice will be very gratefully recieved.
Thanks as always
Steve....................