There are many instances when you lost your PAN card and forget PAN number too. There is no logic in applying for new PAN number and it's is illegal also. The solution is to apply new PAN card with your existing number.
This article will explain how to search your Lost or Forgotten PAN number online.
Step 1 to search your Lost or Forgotten PAN number online
Goto official website of Department of Income tax at https://incometaxindiaefiling.gov.in/e-Filing/Services/KnowYourPanLink.html
You'll get screen like this:
Step 2 to search your Lost or Forgotten PAN number online
Enter the required information like your name, Date of birth etc. and click on submit.
In the next screen, it may ask for your father's name and some other information. Just enter them and submit the form.
You'll get details such as PAN, name of PAN card holder, jurisdiction and status.
Still having problem? Just mention in the comments below and we'll try to help you.