Hey there tizz,
I am sorry to hear that your Chromecast won't connect to your Wi-Fi! Networking issues can be tricky, so I'd be happy to help you out. What I recommend for now is that you follow the troubleshooting steps listed in this article. Let me know if you run into any more issues.
I look forward to your response! If you had any more questions or concerns, feel free to let me know.