Sorry to say this in such a blunt manor, but when love is gone, it's gone. You can't force your way back into someone's heart if they don't want you there. That said, I personally think that the best thing to do is to explain to her what you just said here, ask her if any part of her still loves you or would consider being with you... and if so then ask her what you would need to do to regain that lost relationship. If she says that she does and that there's something you can do, great, you do it. If she says that there's not and that she doesn't love you like that anymore, then it's over... and you'll just have to move on.
Be careful with your heart, because when someone seems too good to be true, they usually are.