2004 mustang, v6, car wont start, stock alarm goes off

i haven't driven my car for a while , last time was 5 months ago, I have an 04 v6 3.8L 29th anniversary mustang. I last time i drove it, there were no problems. When i tried plugging the power wire back to the battery, there is a constant loud horn sound, im thinking it is the stock alarm. I tried turning my key from off to the ignition twice, to toggle the alarm, because im guessing thats what is going off. the car wont start. Im thinking, i armed my car with the stock alarm and when my battery died(i forgot to unplug my battery), it was still armed when i plugged the car in with a new battery. But, i dont get why my car wont start, because i dont think the stock alarm has a kill switch to the starter if it goes off. Maybe no gasoline?? but if there was no gas in the car, wont the engine still crank?? i lost my stock alarm remote, and i really dont want to get a new one, what are my other options????