While you can get a duplicate paper copy of your 1099-SSA form by calling the SSA at 1 800-772-1213. The SSA sign in procedure has changed. Now, you must create either an ID.me account of login.gov account. Once you've done that, you will be able to download your 1099-SSA from the SSA website. If memory serves me right, it's under the Message page.
https://www.ssa.gov/manage-benefits/get-tax-form-10991042s
Maybe you can describe why you can't access your 1099-SSA online. Was it because you haven't created a new ID.me / login.gov account or may be your info has changed for the 2FA or may be you couldn't locate it on the SSA website.
