If you've lost your PAN card and forgotten your PAN number, there are several ways to retrieve it. You can try using the 'Know Your PAN' service on the Income Tax India e-filing website if your details are linked. Alternatively, contacting the Income Tax Helpline or your bank can help you trace the number. If all else fails, you may need to visit an Income Tax office or contact an authorised NSDL centre to apply for a duplicate PAN.