My email account was deleted. Now I can't access my Facebook because the username was Gmail. I don't have the same phone number to get code and don't know the answer to the security question.
What do I do to access it?
You can still login using same email address (deleted one) if you know your Facebook password. Once you logged into Facebook change your primary email address.
If you don't know your Facebook password, and you don't have access of associated email address, phone number and you also don't know answer of security question, then it would not be easy to access your account.
You can try this method, otherwise contact Facebook.