Mistakenly unpin them and now they won't come up and can't find a way to re-pin them.
EDIT: u/DriveByRandomInfo was correct! I forgot to include I was speaking about media that was being casting on my home network. It's odd because if you unpin the controls from the bar the media being casted doesn't show up in the notification shade in ChromeOS. You have to start playing something locally, then that media will show up notification shade allowing you to re-pin the controls. Then the casting media shows up again!