Q: While driving at a speed of 40 mph all at a sudden the car speed dropped to 10 mph and stopped with solid check engine light

Hello. Warning lights accompanied with stalling can be caused by many things. If the oil is low I would go ahead and top it off to prevent the possibility of engine damage, however, it is unlikely that low oil is what caused the stalling. Stalling is most commonly caused by issues with the ignition, engine management, or fuel systems. If one of the components, such as a major sensor, the fuel pump, or the ignition coil, go out or have an issue they can cause the engine to stall. If the vehicle is no longer starting then it may be possible that there is an issue with the electrical system as well, perhaps a faulty battery or alternator. If the alternator goes out it will eventually drain the battery, which could also cause stalling. Scanning the computer for trouble codes, once the vehicle is started, will likely reveal some insight into what the issue may be. As the possibilities could be many, I would recommend having a professional technician, such as one from YourMechanic, come to your location diagnose what may have caused your vehicle to stall.