TV sound problem. Hirecently an old goodmans standard 14 inch tv has got problem on the sound

Question

Hirecently an old goodmans standard 14 inch tv has got problem on the sound output. unfortunately i am not sure about the model but it has remute control and mono sound output. indeed the tv had some problem before that was by tunning the sound vey up the noise would be high on the output. recently regardless the high noise it was tune to the highest possible but suddenly the sound was just gone. yet you can hear a very low sound by putting your ear on the amplifier! even at the highest possible sound tunner. i guess some thing should be replace but have no electronic map of the design board (sound chip) could you let me know what probably shoud be replace and how can i find the pice. thanks in advanceMahps. i have checked the amplifier and it works coorectly so the problem is in tv.