The Cowboy Cavalier (1928)

A girl loses her memory when she witnesses her uncle's murder. The murderer, intent on obtaining a written confession from her that she killed her uncle, kidnaps the girl, but she escapes. The trauma causes her to lose her memory and wander into a town where young deputy Buddy finds her. Buddy takes her home to stay with his mother, who names her "Cindy." Buddy eventually discovers that the girl's cousin, expecting to inherit his uncle's ranch, hired the killer. The deputy solves the mystery, rescues the girl, who has regained her memory, and marries her.