But I'd be fishing around the player app to see if it has some setting for what speaker to use. I can't find a manual for the stock app.
My Galaxy SII stopped playing audio unless I have speakers plugged in. I have tried rebooting my phone, taking out the battery to no avail. When I play a ringtone, it will play from the phone speaker without an external speaker plugged in. Keytones also work from the phone speaker. It seems that only music will not play as if the phone thinks I have speakers plugged in when I do not. I have tried pausing audio and remiing speakers several times. I have tried not pausing audio and removing speakers several times.