I'm going to guess that the 'nh' after your screen name means New Hampshire. That means any hydrangea blooming in May in your area was a greenhouse or florist's hydrangea. These most often are old wood flowering macs, so a single bloom period is typical. Once all the existing flower buds have opened and bloomed, that's it for the year. Lack of flowers does not signify a plant is dead. Are the leaves still in place? How do they look? If good-looking foliage now, proper care for the rest of the growing season and appropriate winter protection should ensure the plant survives winter and blooms again next summer.

If it is still alive in leaves, it will bloom again next year, but they like a lot water and compost. If you post I photo I will try to access it for you.