Hello aspirant,
You can re-download your lost CAP allotment/selection letter by logging into the official CET Cell/DTE website using your application ID and date of birth. Look for the “Download Selection Letter” or “View Allotment Status” section under CAP allotment. Submit your login credentials, select the relevant academic year and round, and re-download the document.

If the letter isn't available online, contact the concerned authorities—either the CET Cell or your allotted institute—to request a duplicate copy. You may need to send a formal request or email, quoting your application number and allotment details. The second copy is usually provided via email or can be collected from the college office.