This website goes through the movie
Loose Change and debunks literally every single line in it, and with it just about every 9/11 conspiracy theory. Beyond that, if 9/11 really were some sort of conspiracy, then tens if not hundreds of thousands, if not millions of people would necessarily have to be in on it, and yet
not one has come out claiming that 9/11 was a government conspiracy. That's rather remarkable considering that people do that with the JFK assassination semi-annually, and actually
get their stories in quasi-respectable publications.