Firstly, try to restore the TV back to the factory settings: press the Home button on the TV remote. Then select Settings-->Device Preferences-->Factory Reset ...
Before you attempt to mirror to a TV, be sure the TV and the laptop are connected to the same network. Can't go wireless? Connect the HDMI cable to your laptop and your TV. MacBooks can use an ...
You can share music, photos, videos, or just mirror your entire computer screen on a larger display. Most Apple devices have AirPlay and Screen Mirroring options easily accessible via Settings.