Search your emails. It will be there in your equity statement.
Check with your bank. Your bank account would have linked with PAN.
Check your bank statement, some IT refund will have come which will have your PAN number
Check salary slip. Check form 16 or any other ITR form which is not password protected.
Check the Mutual fund statement or log in to the MF portal.
Check your cupboard, sometimes some photocopies of the PAN card would be lying somewhere.