Submit to your BDO branch a notarized Affidavit of Loss of Passbook.
Excerpts from BDO Kabayan Passbook's Rules and Regulations:
2. DEPOSIT PASSBOOK -- Upon opening of a savings account, the Bank will furnish the depositor a deposit passbook in which all deposits and withdrawals made by the depositor will be entered by the Bank.
A depositor must, under no circumstances, write anything on the passbook, as the Bank will not be responsible for any sum not properly recorded and acknowledged thereon. No entries other than those effected by the Bank itself shall be recorded in the passbook. In the event of any discrepancy between the entries in the passbook and those appearing in the records of the Bank, the latter shall prevail.
No deposit or withdrawal will be permitted by the Bank unless the passbook is presented by the Depositor. The savings passbook should be carefully kept by the Depositor.
If the passbook is lost, mislaid or stolen, the Bank should be immediately notified by the depositor in writing by executing an Affidavit/Declaration of Loss to be duly notarized and submitted to the Bank. Consequently, the Bank will not be held liable for payments made to any person who shall present such passbook if no Affidavit/Declaration of Loss was submitted by the depositor prior to the payment.
The savings account may be closed and a new account opened or a replacement passbook may be issued under the old account number at the option of the depositor. In either case, the Bank will enter the balance outstanding to the depositor's credit as shown in the books of the Bank.