I just received my W-2 for employment of 2021, and need to add the income to my federal return, but it says my return is already filed. How do I add the income?

In December I received an email stating I could fill out information on my federal tax return to get a head start before my W-2 came in and I could add the income later. But now it's saying I already filed my federal return and I can't add the income.