PC/TV HDMI splitter resolution stuck

Greetings PC gods it is I and I am calling to you in my several hours of need, I'm losing my mind attempting to figure it out. So I hooked up my Samsung TV to my PC to use while also keeping my PC monitor plugged in, worked fine till it didn't I loaded up a game and not it's not working anymore, now it is telling me my resolution is not supported cause it's stuck at 720x480 and I have no idea how to change it back or revert it. I've tried a new cord, hard resetting my TV, praying to the machine spirit and nothing is working so I require your help.