Reach out to your Legal Services or Legal Aid program for your state or region of the state. See federal Legal Services Corporation website and its “Our Grantees” page, https://www.lsc.gov/grants-grantee-resources/our-grantees, for a link to the grant-funded program in your state or region of the state.
Reach out to your Protection and Advocacy Program for your state (many have the “Disability Rights” in their program name). See National Disability Rights Network website, www.ndrn.org (see the U.S. map on their home page, under the description, “Find Help in Your State”).
Reach out to private attorneys in your area who may, for a fee paid through back benefits, agree to handle an SSI appeal. A search for the bar association in your county or region of the state may be the best way to find private attorneys who handle these appeals.