My device is
Sprint Samsung Galaxy S III
I want to do this, because I want to stop the camera shutter sound. And I don't want to root my device.
There is absolutely no way to do this without root, and for a good reason.
If an app was do do this imagine the havok that would ensue?
You will have to root your device, either temporarily or permanently, to do this.
You could physically remove or block the speaker. That would prevent the camera from making a noise (no, plugging in headphones won't prevent the external speaker from making a shutter sound).
Aside from that, you really do have to root your device. Or at least put a custom rom on your device (which usually requires root or an unlocked bootloader, not to mention that almost every custom rom has root enabled by default).
Yes You can change system.files without root through ADB by booting TWRP or CWM temporarily and by mounting system in options .
You could create an updater-script to access the system and mute the shutter sound, without rooting your phone. http://www.freeyourandroid.com/guide/introdution_to_edify
You should include an update-binary and an empty line at the end of the updater-script.