Yes, you will be eligible to appear for JEE Advanced in 2025 and 2026.

The eligibility criteria for JEE Advanced allow candidates to attempt the exam in the year they complete their Class 12th and one consecutive year afterward. Since you are reappearing for Class 12th in the academic year 2024-25 due to health reasons, your official year of Class 12th completion will be considered 2025. This means you are eligible to appear in JEE Advanced in both 2025 and 2026.

The authorities understand that candidates may face unavoidable circumstances, such as health issues, that require them to defer their studies. Eligibility for JEE Advanced is based on the year in which Class 12th is completed, not the year it was initially scheduled. Since you are completing your Class 12th in 2025, you meet the necessary timeline to take JEE Advanced in the next two consecutive years.

Make sure to fulfill any other specific requirements, like the minimum marks criteria in the necessary subjects. Focus on your health and studies, knowing you’re fully eligible to pursue JEE Advanced when you're ready.