I have a 52 inch Toshiba and until recently I was using it as a monitor with my laptop. Then all of a sudden it says no signal and won’t connect. I am using a VGA cord. I tried it on a different TV and it works correctly on my second TV. Is there any reason it would just stop working on my Toshiba, but it works on my Sony 32 inch? What can I try to get it to work again?