We appreciate you letting us know about your Roku device having a black screen but still can hear audio. We would be happy to look further into this issue but we will need more details. Can you please provide us with the following information:
What Roku model device are you using?
Does the issue only occur on a specific channel or all channels on your Roku device?
What troubleshooting steps have you taken so far to try to resolve the issue?
Does restarting your Roku device help resolve the issue?