Ouch, sounds bad, Archie! About the only thing to do at this point is to wait until warmer weather, and prune off anything that doesn't sprout. That's assuming that severe cold damaged it. Other problems would have other solutions, but should have shown symptoms the previous fall, or shown up after sprouting.

If the branches are brittle, those branches, at least, are dead. One way to check for life: go farther down the branch, and scratch off a small amount of bark. If the inner bark is still moist and green, it's still alive, and may sprout from near there. Good luck in this--Japanese Maples are only listed as hardy in USDA zones 6-9.