Middle diff dead?

Hi chaps, I was out on salisbury plain earlier and got stuck in a rather muddy trench so I was in low box diff lock at the time and started moving back, it moved a few inches then I drove forward again any way I kept doing this and getting further and further until 'clunk' and the rear passenger wheel starts spinning with no power to the others.
I've tried re engaging it etc and nothing happens the lever goes into possition but I can't feel it engaging anything and it just flops about?
Have I destroyed the diff or am I being a #### or both?
It's a 110 with a disco 300 and disco r380 with lt230 box.
Thanks in advance,
Nick

does it drive without being in difflock?

Could be front half shaft gone