The Idea Factory - My Prom Date is Alive

A girl dies at seventeen in the 1800s. She comes back as a corporeal ghost in present day to find the house that she grew up in (and died in) was demolished to make room for a high school. She (figuratively) haunts the place for a week or so, trying to acclimate to the new world around her. But she gets caught by someone at the school after hours. They start to date, culminating in going to the prom together.