My child's father passed away last year. There was a child support order in place since she was born. He made a couple of payments but he still owed thousands of dollars in back child support someone told me I need to go to social security, my daughter is not a minor so I was wondering if this is true
Your daughter may qualify for surviving child's benefits if she is unmarried and either a) under age 18, b) 18 to 19 and in secondary school, or c) became disabled prior to age 22 (https://www.ssa.gov/planners/retire/yourchildren.html).
Social Security benefits can be garnished for court ordered child support, but it doesn't sound like that's what's involved in your case.