I don't know the reason of its cause but I have found a solution. Okay, make a call to one of your contact numbers. As soon as the dialing screen appears, activate/click on the loudspeaker button. After that End the call. There you go, it is fixed! :-). Play your music again, the internal speaker will work just fine. Please note that the call does not need to go through to ringing at all. Otherwise there will be a missed call or the person would pick the call by which you would have to explain everything (and make Xperia L a loser:-)). I think you can fix the problem in any way by activating the loudspeaker through other apps like FM Radio, etc., but for me simply making a phone call everytime is more than enough 🙂
