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I am sorry to hear about this situation. Then, someone in your situation can file a DS-5525 (Statement of Exigent/Special Family Circumstances). This is an application filed with the main application, explaining the non-applying parent's or guardian’s unavailability and recent efforts made to contact the non-applying parent. You may also be required to provide evidence (e.g., custody order, incarceration order, restraining order) to document your claim of exigent or special circumstances. See HERE.
Then, it would be up to the US Department of State to decide whether or not to grant it, at their discretion.
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