Can you move the bike by pushing it? Is the back wheel well of the ground when the bike is on the centrestand? Have you got a hugger fitted?Have you tried running the bike in gear on the centre stand to see if you can spot/hear anything oddTry slackening the rear wheel spindle so it can turn then try moving wheel, if it's seized bearing the wheel should turn more easily. Remember to tighten spindle afterwards before riding bike again!
Sounds like a totally seized bearing. Be as well replacing both wheel bearings and the sprocket carrier bearing