u/Constant-Custard

Hi
I have had a personal tax account which I access through the HMRC app, a couple of months ago I logged in and changed my married allowance.

I recently tried to log in to submit my self assessment, but HMRC now say there is no tax account linked to either my email address and the 12 digit number doesn’t exist.

I’m very confused, do I create a new tax account and login or get in touch with HMRC?