I would first follow these steps to reconnect your Chromecast to Wi-Fi.
If those steps don't work:
Hey there mjtomlia,
I'm real sorry about the slow response time, but I would encourage you to check out this article and follow the troubleshooting steps listed. If you are still running into any issues, give the steps listed in this article a try.
I look forward to your response! If you have any more questions or concerns, please feel free to let us know.