Lexus Rx300 Beeping And Now Wont Start

[Annchapman44]

I have a 2000 Rx300 and for the past two days it has been beeping when i start the car and then change from drive to other gears and two days later it wont start!! the car has power...radio and everything goes on but wont start!! Now that it wont start it still beeps sounds like a truck reversing and does two short beeps before stoping