I don't know the cause of your particular problem.
However, I did have a large wisteria, which died quite suddenly. All of the stems and branches were dead. Somehow, the roots were still alive and the following year it threw up some small suckers. These have now redeveloped and grown, and the plant has now regained pretty much the size of the original plant, though it has taken a few years to regrow.
Many wisterias sold in garden centres are grafted. It is possible for the top to die, and for regrowth to come from the root stock, which may be more vigourous.