Immediately notify the issuing bank in writing about the lost cheques, specifically mentioning cheque numbers 072691 through 072694.Request a stop payment instruction from the bank to prevent any potential misuse of those cheque numbers.Apply for a duplicate passbook by visiting your bank branch directly, as this is the standard procedure for replacing lost banking documents.File a police report regarding the lost belongings to create an official record, which may be required by your bank for issuing new cheques or documents.