Thanks for reaching out. The Chromecast devices can only remember one Wi-Fi network at a time. If you changed your Wi-Fi network and your device isn't currently connected to a Wi-Fi network, perform a factory reset and set up your Chromecast.
Let me know how it goes.
Just checking in to make sure that you've seen my response. Please let me know if you still need help or if you have other questions or concerns as I will be locking this in 24 hours. Feel free to start a new thread and we'll be happy to help.