How do I proceed to file humanitarian revalidation for family petition denied due to death of petitioner?

Was the petition previously approved by USCIS? Were you notified that file was returned to USCIS for revocation? You will need to submit a request for humanitarian reinstatement. There is no form or special format that must be used. You will need to submit a new Form I-864 from a substitute sponsor. A substitute sponsor must be (1) U.S. citizen, national, or lawful permanent resident; (2) at least 18 years of age; and (3) the beneficiary's spouse, parent, mother-in-law, father-in-law, sibling, child, son, daughter, son-in-law, daughter-in-law, sister-in-law, brother-in-law, grandparent, grandchild, or legal guardian. In addition to a Form I-864, the beneficiary should submit evidence that a favorable exercise of discretion is warranted including: (1) impact on family living in the United States (especially U.S. citizens, lawful permanent residents, or others lawfully present); (2) advanced age or health concerns; (3) lawful residence in the United States for a lengthy period; (4) ties or lack thereof to your home country; (5) other factors, such as unusually lengthy government processing delays; anD (6) any and all other factors you believe weigh in favor of reinstatement, with supporting documentation. I encourage you to work with an attorney.