Itunes wont open!!!!!!!!!!!!!?

Itunes doesn't work on my computer anymore for some reason, this happened a while ago but I've been so busy I haven't gotten a chance to look at it til now. I've tried uninstalling/reinstalling it as well as quicktime player many times and it still wont open. The Data Execution Prevention (DEP) feature keeps popping up on my computer that is preventing Itunes from working. How would I be able to get this to work?