Greetings,
Here are some of possible ways that you can consider :

1. Contact CBSE Patrachar Vidyalaya:

• Reach out to the CBSE Patrachar Vidyalaya in Delhi directly. They might have records that could assist you in recovering your roll number and obtaining a duplicate certificate.
• Be prepared to provide as much personal information as possible, such as your name, father's name, approximate date of birth, and any other details you remember.

2. Visit the Regional CBSE Office:

• If you can determine the region where you registered for the exam, try visiting the respective CBSE regional office. They might have records or be able to guide you further.

3. Check with Previous Schools:

• If you attended any regular school before enrolling in Patrachar Vidyalaya, they might have retained some records, especially if you took admission through them.

4. Explore Online Resources:

• While unlikely, there might be online forums or communities where people have faced similar issues. Sharing your details (without compromising personal information) might lead to helpful suggestions.
  
  I hope this information helps.