Sorry to hear this - Let's try and sort it out!
Have you followed instructions below:
If so, what message are you getting?
A last chance of resolving this would be a factory reset of the Chromecast - Have you tried this?
It looks like we haven't heard back from the OP so I'm going to go ahead and lock the thread. If you have any further questions or concerns, feel free to create a new thread.
Have a great day,