Sad about Melody

Melody, my cat, has vanished off the face of the earth. She is 7 years old, fixed, and NEVER wanders much more than to the yards adjacent to our own. She has never 'disappeared' for more than a few hours, and always shows up on our deck or at the front door.
But she has been gone for almost a week. This makes NO sense to me at all. If she was in a fight with a raccoon, another cat, or a car, where is her body?
Middle-aged cats don't just suddenly decide to go adventures, as far as I know. She was also healthy, having recently been to the vet for her checkup and shots. So she didn't go off somewhere to die.
Scenarios run through my head: she was hit by a drunk driver, who took her body to hide the evidence. She was 'cat-napped' by someone who is keeping her indoors. She did get in a fight with a raccoon, who dragged her into the nearby woods.
I have put up signs but only one very nice man called. It wasn't my cat, though. This one had gray in it.
I pray someone has my cat and is taking good care of her. I also pray they'll slip up and leave a door open, so my sweet baby will make her way home. But before she does that, I hope she scratches up all their furniture and throws up hairballs on their bed!

Meantime, I am keeping busy. I've heard of cats coming home after years and years--even across the country. There has to be hope, or we'd all go crazy.