If you usually sign in via your Google or Facebook account and you have forgotten your password, you will have to restore it via Google or Facebook.
If you have created an account on the GCN website or the app using your email, all you need to do is click 'Reset password' from the sign in page on the App, or 'Forgot Password' on the web player (here - auth.playsportsnetwork.com).
You will receive an email with further instructions on how to reset the password and login into your account again.