Don't forget, its just an engine. It needs fuel, spark and air to run. If it doesn't get one of the three, I'd guess spark to start, because air will usually get there, and fuel system components don't fail as often as the ignition system (In my relatively limited experience). So do the simple test, unscrew a sparkplug, plug it back into the spark plug wire, and ground the sparkplug to the engine block. Start the engine and look for a nice fat spark. If present, turn off engine and repeat for the next cylinder. If you don't get a spark on any of the cylinders, you have a winner (or loser?). It might be a safe bet to replace the coil pack at this step, unless you want to jump into further diagnostics and probe the driver circuits for the coil packs with an oscilloscope, but that's generally beyond the scope of the typical backyard mechanic's diagnostics. Buddy's Focus had the same problem with missing, coil packs fail more frequently than you would expect from a solid state device. Check for unusual spark plug color or texture and condition while they're out. Its unlikely that so many of them are gapped incorrectly to produce such pronounced misfiring, especially all of a sudden, but you never know. If all of the spark plugs make a spark, then its time to move onto the fuel system. That could be a bit more tricky.
Also, make sure all your connectors are secure, especially the ones going to the coil pack and fuel injectors.
2005 Yamaha Zuma YW50, 2009 Kawasaki Super Sherpa KL250