I had that happen with a submersible heater, and it was, indeed, deader than a doornail.
How long was it on and out of the water? If it wasn't for more than an hour or so, you might plug it back in, stick it in a jug of water (no fishies), and see if it works still. (Put in cold water, then put in the heater with a thermometer and see if it comes up to the correct temp.) That way you'd still be safe with your fish, but you can test it out.
The filter will probably still work, you can test it out and see. :) It'll be obvious within a few minutes. :) I had one I did that with, and it was always louder afterwards, but still works fine. :)