"speaker for talking, not for music"に関する回答1st. I will assume that you used a EARPHONE jack.? It is possible that you cracked the circuit (ckt) board to prevent the signal from getting to the SPEAKER & audio JACK. The best thing that could have happened, was the WIRE that comes from the ckt. board ripped or pulled from the EARPHONE jack or the board itself. If you know how to take it apart, look there, if not get a tech to do the repairs.
"Is it possible to change/upgrade my Graphic Card on my PC?"に関する回答2nd question: If you have a still alive, good warranty... Yes you would void it. 1st question:I agree with "Wakitech", BUT...I would suggest getting an EXTERNAL [ and connect it to the external video in back of laptop] computer monitor & download the latest software for such], because I suspect you want to play GAMES [ or gaming computer ??!!]