Displays Monitor 'No Video Found' When Main Display

Hello,

I have been using the same set up for just over a year now and yesterday my monitor (which is just a TV with a HDMI port) stopped receiving signal.

I can boot up the pc and get the BIOS, which I can go into and see everything fine, as well as the windows loading icon but when it would normally go to the log in screen I get nothing.

I can however plug in an extra monitor (an actual Samsung monitor) with a VGA cable and it all works fine and on top of that if I connect the TV at the same time it works perfectly fine as a second monitor.

However if I try to turn off the VGA monitor and just use the HDMI TV then I get no video signal again.

No idea how to get my main TV monitor working again. Totally stumped.

OS: Windows 8.1
Processor: Intel Core i5-4570 CPU @ 3.20GHz
RAM: 8.00GB
Video Card: GeForce GT 620
MOBO: Asus Ranger VII
PSU: Corsair 500w
Monitor: Technika 22" HDMI + Samsung SyncMaster 2032 VGA