If you have lost your PAN Card and don't remember the Permanent Account Number as well. Still you have a option to know you PAN and re-apply for it.
You can retrieve the Number by entering the required data from the below link. Once you have recovered your Permanent Account Number from the link, you can apply for a duplicate PAN by making an application in the form titled "Request for New PAN Card or Correction in PAN data". The form can be downloaded from the websites of UTI Technologies Services Ltd (UTITSL), National Securities Depository Ltd (NSDL), or the I-T department.