The girl was rich, she fell in love with the stable boy, the mansion burns down, the girl runs back for stable boy, they both die, the wake up along time later as ghosts, the mansion is rebuilt and a new couple lives there, the ghosts try to communicate with the couple and succeed, and they have to figure out why they are ghosts, and there is a note hidden in a clock that they have to find.

Sounds like The Time of Their Lives (http://www.tcm.com/tcmdb/title/93379/The-Time-of-Their-Lives/#)