Oh, Laura, that is so hard and it's painful for me to read as I was basically B at that age. I partied hard, failed/dropped out of college, and was pretty much going nowhere fast from about 20-23. My parents had paid for school and living expenses until I dropped out. Then they told me if I went back to school, they'd cover school expenses, but I had to cover my own rent, food, etc. Here are the two things that finally turned me around, and unfortunately they are not things you can force:
1.) I moved from San Diego to a smaller, less party friendly town (to live with my boyfriend at the time!), so I was out of my party girl environs and settled into a relationship.
2.) The first job I got in the town was with someone I went to high school with and she was an accountant who had graduated from USC. I was the receptionist. It didn't take me long to be all, "Huh. Look at how well Jen is doing over there! I don't think I really want to do this job for the rest of my life."
So I figured out what major I wanted (English - was Journalism), enrolled in classes at the local junior college and transferred as a Junior to a local state school. My parents kept their word and covered school tuition and books, but that was it. I had to (and did) find a job that worked with my school schedule and paid me enough (barely) to live. And I graduated in 2 years!
I guess that's a long way to say he is young and there is still hope. I think you're going to have to employ some tough love to get there, which sucks. Hugs from a reformed crazy party girl!