Q: cranks, but won't start.

If the vehicle was operating immediately prior to the repair work, and you suspect that the timing belt might be mispositioned, then yes valve timing would be the first thing to check. Once you verify the timing, if the starter motor is turning the engine over rapidly, at sufficient RPM, but the engine does not catch and run, that means that there is an ignition, fuel, air induction, or mechanical fault in the engine that will have to be repaired. Strictly speaking, you should first check engine compression in the cylinders because if there is no, or inadequate, compression the engine won’t run under any circumstances. If compression is found to be within factory specifications, and there is fuel being delivered by the injectors (not just "to" the injectors) and the ignition system is working, that means that the air fuel ratio of the mixture delivered to the cylinders is so far off the mixture won’t ignite. Such could be due to an air induction fault like a stuck idle air control valve or, considering fuel, could be due to a failed temperature sensor that must be working properly to signal the PCM to enrich the mixture on cold start. Regardless of the underlying cause, if you request a no start diagnostic the responding certified mechanic will get the problem diagnosed and repaired for you. Please let us know if you have further concerns or questions as we are always here to help you.