Hydrangeas in our region have been heavily hit by multiple late frosts this spring.  A warm spell earlier may have coaxed them to leaf out early, so the damage is remarkably widespread.  There is no treatment.  Prune off dead woody tips.

It will recover somewhat.  If flower buds were not affected, you should get at least some flowering.  In most cases, primarily leaves were affected.  New growth should hide some of the brown foliage.

Ellen