No matter what I try to do my Philips Roku TV has no sound at all. I’ve restarted it, reset the audio and picture, unplugged and replugged and still nothing.
About the only Roku-related thing you have left to try is a factory reset.
How to factory reset your Roku® streaming device | Official Roku Support
Beyond that, it's time to contact Philips.
Where to get support for your Roku TV™ | Official Roku Support