Hello Neha, It's a good thing that admission to US universities is not only based on marks. The whole application process is different. The US colleges put much focus on the overall quality of students and the statement of purpose is very much important. Given that you have not scored well in the 12th and graduation, you need to make your application stronger by putting other stuff like co-curricular achievements and anything other that you can add about you. I am sure you will get admission there.