Chromecast

Ok, I used to be able to cast anything from my desktop to my smart tv. Watching YT? I could cast it to the big screen and watch it there. Normally in Google, I would go to the index and select "cast", it would then discover my tv on my home network, and I would just choose it. Now, when I select cast, it says "no devices found". What the hell happened? I can cast from my phone to the tv still, just not my pc. Any ideas?