Here are some steps you can take to try and recover your 2nd-year hall ticket number:

1. Contact Your College or University: Reach out to the administrative office or examination department of your college or university. They should be able to provide you with a duplicate copy of your hall ticket or assist you in recovering the number.
2. Check Your Previous Academic Records: Look through your academic records, transcripts, or any other documents related to your second year of study. There might be a reference to your hall ticket number.
3. Search Your Emails: Check your emails for any communications from your college or university regarding your second-year exams or hall tickets.
4. Contact Your Classmates: If you can remember the names of some of your classmates, you could try reaching out to them and asking if they remember your hall ticket number.

If you're still unable to recover your hall ticket number after trying these methods, it's crucial to contact your college or university as soon as possible.