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I am sorry to hear about this situation. Your first step should be to make an appointment with Infopass and talk to an agent to see if there are any issues. While often the same information can be received via telephone, in person, the agents tend to be more specific. See HERE. You can also track your application HERE, and see more specific wait times HERE. Applications that are N-400 normally take about 6 months to process. At 16 months, this is unusual.
If you cannot get relief at all and there is no information, someone in your situation may consider filing a Writ of Mandamus. See HERE. This is a type of legal pleading that asks the court to order USCIS to make a decision on an application. This is a last resort step, but may be necessary.
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