macbook pro screen wont mirror to tv that is connected with HDMI cable

I have my macbook pro connected to my tv with an hdmi cord but, the macbook pro screen will not show on my tv.

when I connect and disconnect the hdmi cord my macbook pro's screen blinks out for a split second like it does when it is about to project its screen to my tv but, nothing happens after the blink.

what do I do?

pushing option for the pop up button that is supposed to list all connected monitor type devices does not stay on the screen for me to select it after pushing option and if I hold option down for it to stay on screen for me to select it, after I select it nothing happens.

Please help super fast.