I ended up having to leave school my last semester of my senior year (was only taking 2 classes with credits I needed) due to family issues, then later went to get my GED.  I was taking all AP classes, and lost a lot in leaving.  I suffered from feeling like a loser, despite of my current success and higher education, especially since I only had a few months to graduate.
Sometimes circumstances simply don't allow you to continue.  I don't remember how well I did on it, just that I passed.  I didn't study, or prepare in any way really.
Good luck to you.