2006 Scion tC won't start
 

I have a problem with my 2006 Scion tC we just did a headgasket job on it and put it back together and it just cranks but won't start. It's getting fuel and spark and checked the timing 3 times and nothing. Only code showing is mass air flow and replaced that and still nothing. And no more codes are showing. I'm lost on what to do