What video card do you have?
With the HDMI cable plugged in, go to the Video Card control panel, (eg) nVidia, AMD, Intel etc, either by clicking it's icon in the taskbar or in the Windows Control Panel. Once you load the video card control panel, there should be a setting for TV or Secondary monitor. Or go to Settings in Windows and choose Display.
Now go over to the TV and select the HDMI port the cable is plugged into as the input and it should show your computer.
If the Video cards control panel does not show the TV as an input, it's not selected, bad HDMI cable, bad HDMI port on video card.

 

Thanks for the feedback, I did what you said, but it doesn't show my TV screen.
I also tried plugging in my primary monitor with HDMI (normally its plugged in with DVI) but it doesn't show my primary monitor. But when I plug in my TV screen with DVI it does work, so I guess this means my HDMI port on my graphics card is broken? (because I tested several HDMI cables and none of them work)

Btw I have a GTX 770 which I didn't do much plugging/unplugging with so how does that even brake?

 

Hi, good advice from Spunk, you do need a little patience, some times it can take a minute or two for the two to see each other.

 

tried plugging in my primary monitor with HDMI (normally its plugged in with DVI) but it doesn't show my primary monitor. But when I plug in my TV screen with DVI it does work, so I guess this means my HDMI port on my graphics card is broken?

First download and install the latest driver for your card: Drivers | GeForce If that still doesn't work and you are using different HDMI cables in different HDMI ports (eg) TV and Monitor, and it is not working then the cards HDMI port is defective.
To be sure, Troubleshoot your gear (eg) take one HDMI cable, attach it to a Blu-Ray or DVD player and the other end to the TV. does that work? If so, you now know you have a good HDMI cable. And we know the HDMI port on the TV works, now plug same cable into the nVida card on the computer. Restart the computer. Access the nVidia Control Panel, Go to TV Settings. On your TV select the HDMI port on the TV as the Input. if the nVidia card doesn't recognize your HDMI cable, then the HDMI port on the card doesn't work.

 

I tested everything and updated everything, and NVIDIA still won't show the screen I connected with the HDMI, so I guess this concludes that the port is broken

Really strange how it worked just fine, until 2 days ago it stopped working.. and the only thing I changed was a new cable, but the cable works just fine on other devices, and the old cable I used also stopped working when connected to my PC.

 

Troubleshoot your gear (eg) take one HDMI cable, attach it to a Blu-Ray or DVD player and the other end to the TV.

Make sure you troubleshooted your TV and cable with another device. If that works, shut down the computer and plug that same cable in the same HDMI port on the TV into your nVidia card. Then start the computer, if the nVidia control panel still doesn't show the TV, then the HDMI port on the card has failed.

 

So just to let everyone now, the problem has been solved.

The issue with my HDMI that couldn't connect was clearly a broken HDMI port on my graphics card. And now I bought myself a DVI to HDMI cable, and now it works just like it should.

Thanks a lot for your fast feedback everyone, it really helped. I will definitely come back to these Forums if I have some other issues with hardware/software (hopefully not).

Cheers!