Loose ground like the one on or near the thermostat housing could cause the car to have run fine but now not run at all.
Blown fuse could do the same although right off hand I don’t recall if there is a fuse that could go and still let you get spark but I do know the car will easily crank with the ecu fuse yanked.
You rechecked timing after the car ceased to start? Timing belt slippage is very common if not adjusted properly.
Just some thoughts from someone who has debugged many hondas