ls400/1uzfe expert needed

ok here i am again, this time my car decided to just not start one morning. i narrowed it down to a no spark condition then checked the diaganostic codes which confirmed my thoughts. the problem im having is that i have no idea why im not getting spark. id like to solve this problem by only having to fix the one part thats bad, not 20 parts. so if there is any one who knows the motor pretty well id love to have you come take a look or give some advice