Be carefull the bottle did not crack, frozen liquid expands while freezing and may crack or break the bottle.
If not, the fiz will still be there assuming the cap seal was not breached...
On a side note, when I was doing Cheffy things, we used to make champagne jello. The Co2 stayed in solution , while you could see bubbles (looked cool in a layered desert in a tulip glass) the carbonation was still there.