If there is no sign of life then lift the tree and look at the roots they will be dark brown and there is unlikely to be any white or light brown 'healthy' root.
It may also be worth applying some slow release fertiliser into the soil around your tree.
We have however seen more mature trees, having lost lower branches naturally start to produce new growth from lower down the trunk and this could be the case with your tree.
Heavy bleeding, nausea, vomiting, and painful uterine contractions are common features of a process TIME magazine calls "A painful, messy, and protracted." About 2% hemorrhage and more than 1 in a 100 require hospitalization.
It seems in general that the trees need to have -12 to -15 degrees centigrade for fairly long periods to actually kill them (as seen in central Europe in the winter of 2010/11).
There have been a handful of reports of trees not surviving this last winter in the UK but on investigation this has been in the main due to the trees already suffering from a fungal root disease called Phytophthora which is a wide spread and very common disease with the ability to affect many garden plants.