Crown Victoria 2009 all of sudden won’t turn all of a sudden not battery or starter

Hey I own a ford crown Victoria police interceptor 2009 and I drove it to school
last Friday just fine and then after school I went to start it up and it would turn
over. I would get the lights and everything but it simply wouldn’t turn over. We
checked the battery which is pretty much brand new and the tow guy and a
relative who was and is still I think a mechanic checked and the battery wasn’t
the issue. We replace the starter yesterday and it still wouldn’t start. I would
really like to keep the car but simply can’t get it to start.