What do I do about my iPhone 4S

I turned off my phone to charge it. When I turned it back on, All of my data was gone! Everything that was on my phone is wiped out. What do I do? Please help!

Ps. I have owned this iPhone for 6 months now. This has never been an issue.

It sounds like someone restored it. Connect it to itunes and it should copy everything back that you had backed up.
By the way you don't have to shut if off to charge it, I don't think I shut mine off in 3 years now, just flip the little switch in the corner if you want it silent at night, but you never have to shut them off.