when plugged into desktop - does that mean my pc if fine and the speakers faulty?

i have logitech z213 sub and speakers less than a year old.  the sound out of them was never great but they stopped working and the green light on the switch thingy doesn't come on anymore.  if i just plug the two little speakers directly into the pc instead of the sub i can get faint sound but that's about it.  sound with headphones plugged in is crystal clear.