When I was 17 I had 3 wrecks... all were in corners that I took too fast and without the experience... well, I went down. I took about 5 years off from riding before I got on another one. I was nervous as hell in corners, and am still a bit at times. I have recently started taking my bike to the track and have gotten much better in turns. I have been there 3 times, and I am just about dragging my knee in the turns now. 3 times at the track in 3 months with instructor riders has done more for me than the last 2 years I have ridden learning from my own experience.
Take a class or 2, and get some of the basics down again. look into your turns, your bike will go where you are looking. If you look straight ahead when you are turning, that is where your bike will go. point your head in the direction you want to go and dont look away until you have gotten there.