You don't have a previous auto-save, at least?
A couple people who ran into a different problem (dropping through the forcefield on the hatch in the bunker at the start of the fjords) on the PC were able to email their save to Larian (support@larian.com) to place them back inside the bunker. MS made sure to disable USB drives in the system section; short of one of their proprietary, way over-priced memory modules, I don't know of an easy way to get a save off the hard drive.
At least in one case, the problem above cause the dragon stone to stop working; the game disabled the stone during the fight, and did not enable it again since the encounter did not end properly.
One person who ran into this problem, and had a recent save, kept going and the stone started working again after they got the seeds quest in the cave under the waterfall.
