I can definitely relate to how you feel about school. I felt like this most last year, and failed almost everything simply because I didn't care. I wish I could give you a good piece of advice in this reply, but unfortunately I'm still trying to pull myself through it myself. One thing I do try though is everyday when I wake up I think of a reason why school is important for me now and for my future. When I don't want to get up or do my homework I try to remind myself that who I am ten years from now rests on who I am and how hard I work today.
It's not always easy, but remember the emotions of how great it is when you get A's and B's. A great thing to strive for is those moments of happiness, and I often use that as my motivation too.
Best of luck with school (: I'm sorry I can't be of much support, but I definitely know what you're going through. And to be honest, I didn't think your grades were really all too bad!