I just got my acceptance into an ADN program where I live in California and was also in the same boat as you. I had a very low GPA and thought that it would be near impossible to get into an RN program without having to pay a pretty penny (close to $60,000 for a local program). I spoke to the nursing counselor at the school I wanted to attend and asked her what I could do to help my chances. She gave me two goals:1) Get all A's in all courses from that point on and 2) Get a 87 or higher on the TEAS 6 exam. So I focused on those goals and was able to meet them. Every school has slightly different requirements, check with a counselor before you count yourself out. As far as past D's and F's, some schools have a thing called Academic Forgiveness. If you retake classes in which you received those low grades in and can show that you are more serious about your schooling, some schools will have those low grades not calculated into your overall GPA (they will always be on your transcripts though).
Hang in there! If it's something you really want, you will do whatever is necessary to fulfill your goals.