If you're having trouble casting to your TV, it might be due to a number of different factors. First, make sure that both your phone and TV are connected to the same Wi-Fi network. If they're not, you won't be able to cast.
Next, check to see if the Chromecast built-in or Google Cast app is up-to-date. If it's not, update it and try again.
If you're still having trouble casting, there are a few other things you can try:
Restart your phone and TV. This will often fix any connection issues.
Unplug your Chromecast device from the power outlet and plug it back in. This will reset your device and often fix any software glitches that might be causing problems.
Make sure your Chromecast device isn't too far from your router. If it is, try moving it closer to see if that helps improve the connection.
Check for any interference from other devices or appliances that might be affecting the Wi-Fi signal in your home