No sound is coming out of my Bose 321 system.

well a few details would be helpful, we can assume you have it all connected properly? - the manual will help with that. You can check if the source sound is outputting properly using different devices to troubleshoot, or try using a different input to the amplifier - say connect something simple, a phone, cd player, whatever. see if it will do anything at all

Is this a home theater system? How do you currently have it set up?

Do any lights come on or indicators respond to the controls? If not it could be just a fuse, though for a fuse to blow it could indicate a more serious underlying problem. If it has a headphone socket, do you get any sound in headphones? If so, then it'll be a problem with the speakers or the internal speaker wiring. Is it possible a small child has poked something in the headphone socket? That could mute the speakers!