Used a different account when you first signed up.

Hi, I'm trying to sort out a self assessment form and when I try to go ahead and file a self assessment I am met with this statement. You used a different account when you first signed up to view or send you're tax returns online. If anyone could help it would be much appreciated. Regards 

Hi,

If you are unable to locate another Government Gateway ID, please contact our Online Services Helpdesk.

Technical support with HMRC online services

Thank you.