connecting my mac to my TV

My mac will not connect to my LG tv after the yosemite update. I have purchased new cables and i have tried all the resets and still nothing.. my screen does nothing and the tv just displays "no signal"

Before it would work fine every time and now never!!

PRAMS were reset and i have rebooted TV and computer countless times..
I have tried all the different connection processes people have suggested and still nothing.

I need help