best way to do it is start with code that works, and i have been playing with this code for the last hour, so i know it works,
try it out and see if that works, then you will know if you have a software problem, if that works then try your code is messed up, if it doesnt then you have a hardware problem 
P.S.
if that does work you can check out this >>Here<< which is a bunch of tones that work with that code just tryna give you a jumpstart
P.P.S
i took your code and loaded it into my arduino, it is annoying, but it definitely works... so you have a simulator problem, or a hardware problem... if you are going to simulate arduino and have aspeaker you should really look at Proteus, it has a speaker that works throught the headphone output of the computer, and is a much better simulator. DVDdoug is right though swap out your transistor, or try it with a piezo buzzer first, you can salvage them from alot of old junk (smoke alrms, microwaves, washer/dryers computer MB) if you have a headphone jack (female, you can actually connect this to anything with an AUX cable (which is 90% of audio toys these days, including car stereos) just be sure to have the volume all the way down and work it up slowly as to not destroy anything ..