Brightside

Hi there, I already have my UTR and have previously completed Self Assessments as a sole trader but I closed that business and 'deregistered' several years ago. I need to register as sole trader again but for a completely different business. Everything I've read says that I need to 'reactivate' my Self Assessment and re-register as a sole trader but I can't find any way of doing that. I understand that I will need to complete a Self Assessment for 2023/24 but can't see how to register my new trading name, start date etc, now. When I login to my personal tax account, my business account is still there but when I try to 'add a tax' there is no 'sole trader' option. Only 'partnership' or 'trust'. Please could you advise me on how to add the new business? Thanks in advance