Yamaha DGX640 style backing tracks no longer play

by Nicholas
(Mazomanie, WI, US)

Actually you can hear them faintly when the volume is turned way up. Is there a separate set of speakers for style vs song bank and voice that allow them to play simultaneously and so is it possible that I blew out one set of speakers? Or is there a way to give the Yamaha dgx640 a factory reset to undue any digital calamity? Thanks!