Hey there Aju,
I'm sorry about the late response, thank you for being patient! Were you able to fix that Wi-Fi problem? If not, I'd be happy to help out, let me just ask you some questions about what's the issue:
If your Chromecast device is looking for its old network, but you set a new one up, check out this article on how to change the Wi-Fi network on your Chromecast.
I look forward to your response, and if you have any other questions or concerns for me, please let me know!
We haven't heard back from Aju, and it's been a few days, so I'm locking the thread. As always, feel free to make a new thread if you have any more questions or concerns.
Have a good one!