How to I amend last 2023 tax return ?I accidentally filed single. When I should of filed married but filing separately and I’m unsure how to amend this and get my return

You can amend for 2023, but TurboTax e-filing has closed, so you'll be able to prepare your amended return, and then you need to mail it to the IRS.

Per How do I amend my federal tax return for a prior year?, here is how to file an amended return in TurboTax Online:

1. "On the Tax Home screen, scroll down to Your tax returns & documents and select the year you want to amend.
2. Select the Amend (change) return dropdown, then Amend using TurboTax Online. If you're told to amend your return via TurboTax Desktop, follow the steps for TurboTax Desktop instead.
3. Continue through the screens, make the changes you need to make, and carefully answer the remaining questions to finish amending your return."