If your advance parole application is denied, you will receive a notice from USCIS explaining the reason for the denial. Depending on the reason, you may be able to file a motion to reopen or reconsider the decision if you believe there was an error in the adjudication of your application. Consulting with an immigration attorney can be beneficial in such cases, as they can provide guidance on the best course of action and help you prepare any necessary documentation to support your appeal or new application.