@Soloist1 What phone are you using? Are you currently signed in to Google using the same account that you used to register for Stadia?
Our friend, @Ivan , is asking the right questions!
1. What device are you currently using?
2. Is the Google account you used to set up the phone the same one that you signed up for Stadia with?
3. Have you tried accessing Stadia on other devices such as a computer to ensure you still have access?