Golf diesel camshaft problem

Hi everyone!

I have a problem with my 96 1.9 diesel golf.I didn't use the car for a few months and when I started it again, something went wrong and a big clound came out from the exhaust.I opened the valve cover to realize that the camshaft was all worn and that 2 hydrolic pusher were"missing".I'm now taking the head off but i'm wondering what happend!?Did somebody know what could happen?

thanks!