First things first, try that HDMI cable out with another product if you can. If there is no joy, it could be the port on the TV or the laptop which may have malfunctioned. If possibly, see if you can try another laptop, maybe ask a friend to see if they have one which they can bring around to test.
Usually it could be something small. I know in the past, an automatic driver update on my graphics card was the culprit.