HDMI connection to TV won't output sound

I have a Macbook Pro 15" with retina display and a Wii U. I have been using them both with an Asus VE248H 24" TV. There have been no problems until a few days ago, when I turned on the TV and the picture came out but the sound would not, neither with my laptop or my Wii U. My laptop's sound settings no longer even register the TV as an output. I don't know what the problem is or how to fix it. (What may be the case is that I recently tried to use a HDMI splitter cable which ended up not working.) I've tried unplugging everything and plugging it back in, turning it off and on again, etc.