Possibilities,
1. They have lots of resumes and don't have time to go over them. But yours is in their hand, you will probably be called if they are interested in you, but it may take some time... if the job is still open.
2. They already found someone internally. So, they took off the ad.
3. They already found someone outside, you are out of luck.. By the way, if you just applied, don't expect they will send you rejection email. My experience told me many companies don't even bother to reject you by email. Even for interview, after the interviews, 90% of the companies I interviewed don't bother to say that they picked someone else instead. They just leave me hanging..
And on the side note...
I have one interview two months ago, I was told by HR that the top manager hired someone instead, but would recommend to other location, then I waited until now, the location manager never got back to me .. and the ad for both sites are gone. What does that tell me? I have no clue, either they hire someone internally or they just stop hiring for some reason. I did contact the HR, and she did reply to me.. just say please be patience. I will probably email her one time..
But if I were you, I won't count on one job. I will apply more and more..