Please Help Transmission Problem

[znpzmustang]

Ok so i drive a 2000 mustang v6 automatic, today i went out to my car to start it and it wont start. ive had this problem before with it not starting and the reason why its not is becasue the transmission doesnt line up right, like when i am in drive the shifter indicates thats its in the middle of 2 gears but really its in one gear. so ive lived with that becasue i know when im in what gear anyways. my dad is a mechanic and thinks that its the shifter cable, or nuetral switch causing the problem. but my question is has anyone had this problem with there car? and do you think this could be the probem?and how much this is going to cost and what is going to need to be done to repair a shifter cable or nuetral switch. any help is greatly appreciated thanks

[znpzmustang]

also does anyone know where the nuetral switch is on the transmission?