Can you still sign in to your TalkTalk Mail (Webmail) mailbox?
Password recovery may have been set up for the email address with an alternate email and or mobile number. Please do try the Reset your Password option. Other than the reset to the account itself, if there are alternates listed, see if you recognise them from the hints and if you do have access to the alternate email or mobile then please reset the password. Otherwise send the reset to the TalkTalk account itself and complete a password change within 30 minutes or use the Update your reset details option first.
When you do sign in via Webmail you have the ability to set up Reset details for a self-help password change. Update your reset details is an option on the main menu.
When signed in do check there's no Auto forwarding of messages. This would be a reason for not receiving messages.
Select the main menu then Settings then on the left side panel select Mail (or Email) and select Auto forwarding and untick Enable if you see any unauthorised forwarding.
Worth also checking Filter rules to make sure there's no rules present that might be blocking or redirecting messages. Select Disable against any rules to troubleshoot this section.
If you don't have Reset details set up and cannot access the mailbox then you'll need help from the TalkTalk team to secure the mailbox and set up Reset details. I'll alert the TalkTalk Community team for you and you'll receive a response here from Monday onwards.
In the meantime, please update your Community Profile Personal Information (Click here) to include your name, current contact 'phone numbers and address with postcode (location) then scroll down and add the email address to Private notes and Save changes.