Welcome to Justanswer.com, my name is Dustin.I'm sorry to hear about the issue you are having, I will do my best to help you resolve it.
Lets start by trying to master reset the device, this should get the sound working
After it asks you to reset all user data and you tap yes, it will be reset. Then, set it up again choosing your language, and home location. And then see if it has sound now. If this doesnt work or if you get stuck please send a reply and let me know so you and I can work on this issue further.
I strive to provide great service, and greatly appreciate a 5 star rating clicked and submitted when you are satisfied.. I always answer follow up questions.Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.
The video I sent you is very short, and shows you how to do the reset.
Basically, all you do is shut off the nuvi.. Then, put your finger on the lower right hand corner of the touchscreen and keep your finger pressed against the screen.. Now, turn the nuvi on while holding your finger on the bottom right corner of the touchscreen, then when it asks you to reset all user data let go of the screen and tap yes. This will reset it.
Dustin S.Senior Technician and Network Switching Systems Operator / Maintainer.