Car won't start

my 2007 jeep grand cherokee won’t start. when i turn the key it doesn’t even turn over. any suggestions?

I also forgot to mention i can’t even jump start the car.

Check for 12VDC at the starter when you’re trying to jump it. If you have that, then your starter assembly, probably the solenoid, has suffered premature demise. If not, post back.

I let my sister borrow the car. anything could have happened

how do i check for that? (i’m a girl and just recently mastered changing a tire)

Isn’t a 2007 vehicle still under warranty?
Don’t all new vehicles come with free roadside assistance?

If I am correct on those two points, the answer to the OP’s dilemma is to have the vehicle towed, gratis, to the dealership for diagnosis and repair, both of which will also be gratis.

And, it is not necessary for the OP to offer a diagnosis to the dealership. It is the dealership’s job to run through their standard diagnostic protocols in order to determine the nature of the problem, and then to fix it free of charge. Even if a diagnosis is offered, it will be ignored by the service department, as they are required to go through a diagnostic procedure.

Ditto VDC. Rocketman