I have no sounds during calls, neither incoming or outgoing, no sounds for music or anything at any time on my Nokia Lumia 630 (Windows Phone 8.1). How can I fix that?
First, try a soft reset.
If that doesn't help, you should contact Nokia Care.
You can download sysapp pusher and check for update audio setting http://www.windowsphone.com/en-us/store/app/sysapp-pusher/19d44d9e-f18e-4df1-9bce-36335242ed2e
If it not fix your problem, you can try to restart or reset your phone.