I've asked that full access is restored for the lineone mailbox email addresses that you will have added to your Community profile, Personal information, Private notes. (Do check)
TalkTalk Support will respond here and then restore IMAP4 / POP3 access as soon as reasonably possible. Until full access is switched back on, use TalkTalk Mail webmail via an up to date Internet browser to keep in touch with email contacts.
You say you believe you have changed settings. Are you confident that no help is necessary checking services / devices / email software for compatibility with TLS 1.2 encryption and the incoming and outgoing server settings in use? Did you identify the insecure settings, for example? The culprit device or software that got mailbox access switched off because ports 25 (SMTP) or 110 (POP) or 143 (IMAP) were used?
