I logged onto the Health App <https://www.apple.com/ios/whats-new/health/> this morning and all of my data was gone!! Or Was it? I found a post by " on a https://discussions.apple.com/thread/6568048 post that explaned how to solve the problem:
SOLUTION:
1. Press and
hold the power and him keys together.
2. Keep held until the phone has
gone black, the apple logo has appeared and disappeared again.
3. Then let
go of the buttons
4. and turn the phone on.