Bluecray
"I've got a very old ntlworld email"
The key question is whether you have a Virgin Media broadband account?
If you don't, then you need to be aware that VM are actively deleting VM email accounts that are no longer linked to a live VM paid for service such as broadband. Here's their advice about that: Some important information if you have a Virgin Media email account | Virgin Media Community - 5607207
"But I recieve email OK and can send email. "
Are you using an email app or client such as Outlook to send and receive VM emails? When VM close an email account it seems that they often just remove access to the VM webmail account but forget to close the mailbox itself. That means you cannot sign into the account on their website but email apps still work because they access the mailbox without going via the VM webmail account. So that might explain what you are seeing.
"nothing works even says my email isn't about"
These days the error message is usually "This Virgin Media email address isn’t valid ". Are you seeing something different?
Coenoby