E320 cranks well but does not start

Ignition needs 3 things, a spark, a supply of fuel and air and rotation (cranking) and these three are choreographed via timing. Unfortunately you haven't given enough information to say which it is, so maybe start by checking first that your battery is fully charged and then inspect the spark plugs and leads. You will need an ohm meter to test the ignition coils and you will need to find out what the correct values are for your car. If all that is fine you can move on to fuel supply. Quick and dirty check is to disconnect the fuel line from the injector rail and try starting the car. Have a container ready to catch the fuel, it should spurt out quite forcefully. If it doesn't you may have a blockage, a dirty fuel filter or a dead pump. This leaves you with air (for the fuel air mix) and timing to check. You really need a diagnostic computer at this point but you can still try manually cleaning the MAF sensor, checking all the wiring to it and intake temperature sensor for loose connections and removing all the fuel injectors and manually testing them with a 12v source. I don't know your level of experience, none of this is too difficult but don't try to fix it without help if this is your first attempt at DIY.