I agree with washia07's answer -- you need to narrow your topic.
Are you going to examine teen violence in urban areas? As a result of drug or alcohol use? As a response to domestic abuse?
Once you have a better idea of what you'd like to write about, you can start writing down some ideas.
For example, let's say you want to look at teen violence in urban areas. Which specific (geographic) urban area do you want to focus on? Where does teen violence occur in this particular area? You might research bullying in schools, gang activity and recruitment, drug availability and how that leads to violence, and so on.
A great place for looking up reliable articles is ipl -- the Internet Public Library. This will provide reliable, researched studies.