Laptop won't detect HDMI TV anymore?

The laptop is a Lenovo b50-r30 running Windows 10 with Intel graphics.

I had the laptop plugged into the TV yesterday via HDMI and it worked fine. Today I turned both laptop and TV on and saw no picture on the TV.

With the TV still plugged into the laptop I went to display settings and clicked on "detect" and it said "display not detected".

How can I get the laptop to display on the TV?

Luke

Is there more than one HDMI port available on the TV? Is it still selected as the source for the signal from the laptop?
A way to rebuild this is to go back a day in System Restore where it worked. If there's a restore point at the right point in time, that might work.
Try turning on laptop first, or the TV first.

Starrysky