My pc is working fine

Question

my pc is working fine at the moment.in the last couple of days the sound has gone of .we got it back a gain and it lasted for a day.now its gone again.but when you touch the back you can here nose as if the sound is there but not coming out you can here a buff when you turn them on .the sound thing is attachted to the mother board.dont no what to do.im scared to down load anything.can you please help me miss davies