My old gmail and Facebook has been hacked into and password has been changed

You will need to resolve this through Google and Facebook as is has nothing to do with your Apple products. Start with the following:

https://support.google.com/accounts/answer/6294825?hl=en

https://www.facebook.com/help/203305893040179/recover-a-hacked-facebook-account/

If you manage to recover your accounts, here are three very important suggestions to improve your cybersecurity:

1. Never use the same password on different websites or accounts (ever). Use a completely different and complex password for every account.
2. Use a password manager like the new Apple Passwords app to store your passwords or passkeys (Use the Passwords app to create, manage, and share passwords and passkeys across Apple devices - Apple Support
3. Learn to recognize phishing (https://consumer.ftc.gov/articles/how-recognize-and-avoid-phishing-scams)
4. Enable two-factor authentication on all of your accounts (https://support.google.com/accounts/answer/10956730?hl=en, https://www.facebook.com/help/148233965247823/)

Sorry, but there's nothing Apple, or your fellow users here can do about it.

You're going to have to try and contact Facebook and Google.