Love spells are tricky because unless both people are open to it, the chance of it working are slim. And to be quite honest, love spells never usually work. Not to put you down or anything but maybe she just...doesn't love you anymore...I really don't mean to say this to make you feel bad or anything but sometimes the truth hurts and we find any way to make it seem like it's not our fault.
If anything you need to speak with her and just ask her what happened and why. That'll get you a lot further than a love or banishing spell will.