Just installed a new water heater, when I went to turn the water on the main (there was no individual shutoff to the water heater) it snapped off in my hand.

I have a well system, not city sewer. And my main is located in the center of my house, I have no basement. Is there anyway I can fix it on my own? Shut off the power to the pump? Then cut the old one out and replace it? I'm afraid of water going all over the place, but hate calling a plumber at this late stage.

What will the plumber do about it? Approximate price?