Missed Misscarrige

Well ladies I'm out I went to go check on my baby Wed and they couldn't find the baby heartbeat so then they proceed to take me to ultrasound and to see what was going on and there was my baby, just there with no heartbeat at all I had thought my life was over,I just couldn't believe that this was happening to me I'm still sad I still sit there and think like did I do something wrong, But everyone keep telling me there's nothing that I did wrong sometimes these things just happen but I still don't get how your body don't reject my baby that is no longer living, I just don't understand. I was 11 weeks 4 days but they said my baby heartbeat stopped at 8 weeks 6 days