Query: Oh little one where'd you take my heart Oh little one where'd you take my heart Did you hide it in the moon? Did you sink it in the sea? Is it stuck inside your pocket? Keep it close as close can be Someday you'll return to me...

This is a strong match: the distinctive opening and the moon/sea/pocket lines appear verbatim in listings for “Return to Me (Kiran’s Lullaby),” sung by Pavi in Avatar: Seven Havens.