Never Say Die

Cassandra survived the zombie apocalypse. She and other young survivors band together to search the desolate city for food, lodging, weapons, and hopefully, more survivors.
On one such rescue mission, the zombies get lucky and Cassandra is their victim. Instead of dying, though, Cassandra wakes up in her own past, days before the outbreak of the virus that turned all the adults to mindless monsters.
She has one chance to stop it all. Well, maybe more than one.