Your steering wheel might be locked. Try to relieve the pressure on the steering wheel by turning it in one direction or the other while trying to turn the key. I am having a similar issue and I research the forums and came around to that. I am going to try it when I get home myself. Mine problem happened when I locked the steering wheel to remove the instrument cluster to repair my lights and needles. When I put it back in to check out my lit goodness...nothing but a door chime.
Hope this helps.