This story is a sequel to Return to Equestria
Ten years have passed since the death of Sonata Dusk and her sisters are living productive lives as unicorns in Equestria. When that ten year anniversary comes along, the most unlikely pony wants to find a way to revive her and bring her home. This will require one thing, a trip to visit Celestia to restore something she destroyed.
Source of cover art: https://www.deviantart.com/robocheatsy/art/Ponified-Sonata-Dusk-645848850
Rated teen for minor profanity.