I just read this and wanted you to know that you aren't alone. I don't know anything about your situation besides what you wrote, so I could be completely wrong on my assumption. I go through stages of absolutely loving my classes to absolutely hating them and feeling completely unwilling to do ANYTHING. I'm kind of going through that right now. Plenty of assignments, but I just don't feel like doing them. I'm hoping that's totally natural, or else something major is wrong with me.
Don't quit. Push through your feelings and finish strong. I've also had a bad time in the past on antidepressants and came to the same conclusion: they aren't for me. I've been working on my eating habits and exercising more often (still not as much as I should) and I'm taking time away from studying to spend time with people I really love. It's helped me a lot. And I don't know what your friends/family situation is, but I really suggest that you be around people as much as you can (of course keep studying, though). And be around people you really, really like, people that make you feel better about yourself.
I know we can't always control chemicals in our brains or whatever, but we can control our response and attitude towards situations, and if you choose to make this thing work, then I know you can do it.
Don't give up.