Have you tried logging in via webmail:
https://apps.talktalk.co.uk/appsuite/
You could also try creating a new email account somewhere else and using that service's 'mail collector' facility to try to get your TalkTalk emails automatically forwarded to your new account. GMX provides such a facility:
https://www.gmx.co.uk
Or try a call to TalkTalk's customer service line to see if they can help: 0345 172 0088