[Sivik]

I would check the under hood fuses if you haven't done that. Does the radio or anything else work? Is you car equipped with any alarm setup that would disable ignition?

If you car is a manual, have you tried push-starting it to see if it will run?

As far as the crossing the positive/negative, if you car didn't work before you attempted to jump it, I don't think it did anything after you did... unless something has changed since your attempt.

Best bet - get a voltmeter and start checking connections to see what has power and what doesn't.