Ummmm, Kathy, if you do not have any leaves (or see any new growth) this time of year, it's probably a goner. You might want to pick a couple areas somewhere near the base and scratch them. If you don't see any green, you have probably lost it.

I live in Z4, and have had a butterfly bush for a few years. Here, it dies down to the ground and I prune it down to about 6 inches late spring---but, when it comes back, it is more like a plant on steroids. Doesn't get like a shrub or bush---but, it does very nice. Lotsa blooms, smells nice. Unfortunately, with the winter we had (no snow cover, for the most part) it did not survive. I will probably replace it when I get a chance.

I am really no help but I do want to say something about butterfly bushes. I cut mine down in February, but I never get a bush. Mine always looks like a tree. I always imagined that it would be bushy, but there is a very thich stem - is that normal? Thanks

If you still have some green in the stem cut the dead part off and make sure it gets enough water. Good Luck with it!
I am in Zone 7 and got my 3 little (6") plants 3 years ago. I now have 6 large ones and 12 new ones started and have given many away. My largest was cut back to about 2' during the fall and now it is about 12' and then when a bloom is finished I cut it off and it will still grow and have blooms all through summer and most of fall. Very easy to get new ones, when I pune, I just stick some of the limbs in the ground and most of them will root of the soil is pretty good.
Hope this helps!