In any case right now first the closed captions in text mode is turned on and needs to be turned off for that box to disappear .
Press ACTION and go to SETUP >>> CC >>> CC MODE and set it to OFF there and that box will be gone .
Now about the audio ;
I don`t know which problem came first ( sound or black box) but if one was caused while trying to fix the first then you have the answer for the box and if the sound problem came second then try this ;
Press ACTION and go to the AUDIO and open it , first make sure that under MODE it says STEREO , not SAP then scroll further down where it says SPEAKERS and make sure it says ON
For the black box I know that the caption text will take care of that , for the sound , if you still have no sound after that then let me know and we`ll troubleshoot this further .
If that works and you don`t have any more questions for now then please do take the time to rate my answer by clicking on the 5-star icon at the top, then click on Submit , this is how I make a living and that rating gets me paid for my time.
Also note that it will not close this post , you can come back here at any time if you have questions.