Connecting MBP to Magnavox HDMI

Hey guys, an issue just came up with my MBP and my Magnavox TV. For the past couple of months, I have been connecting my MBP to my TV to watch movies and stuff on. All of a sudden, just 2 days ago, when I tried to plug my MBP into the TV, the TV said that the format was not supported. So I'm not sure whether it's an issue with my MBP or with the cables that I have. The adapter I am using is called Rocketfish mini display port ti HDMI, and I just have some random HDMI cable I bought from Target. I'm pretty sure that the cables are fine because my buddy just plugged in his laptop and it works.

Thank you for all your help in advance!