My laptop won't switch on!

Hello,ive got my dads old laptop and its a sony PCG-4C1M.
Basicaly i was searching 4 somethin on it, and then it froze, so i had 2 switch it off with the power buton. then i tried 2 switch it bac on but it wouldnt. the lites went on, and the fan seemed 2 work, but the screen stayed blank. i kept tryin again and again, until it switched on again, but then it froze again. and wen i try 2 recharge it, i think it does, but the litle ligth doesnt flash like usual. by the way i dont hav an anti-virus software, so could it b that? im wonderin if it could b the battery pack, but im not sure.