What will happen if you are a passenger in a car that has a severe accident and you are severly injured The car is uninsured and the driver who doesn't own the car is uninsured?

If there was another vehicle involved and the accident was that driver's fault you can file a claim through their insurance. Otherwise, the only other place to go is through your insurance. You can use your medical coverage (if you have it) and you should have "uninsured motorist bodily injury" coverage that you can use.