My LG KS360 phone can not play more than 1 song

The mp3 player thing I can help with. I have the same phone and it used to do that but then I worked out that you have to press a button when the backlight turns off while the song is playing. So say you're halfway through listening to a song and the screen goes black, press a button so the screen goes colour again. Do this at least once while the song is playing.