hello aspirant

generally when you forget your password, you will have to reset your password by searching forgot/ reset password option then a verification code will be sent to you once you enter your registered email or mobile number and then you can enter a new password.

in case of jee mains, 3 options are available :

1. using Security Question & its Answer you chosen during Form filling

2. Using a reset link sent via Email to your Registered Email address.

3. Using a verification code sent via text message to your Registered Mobile No.

If you could specify for which application you lost password, i can help in a better way.

hope this helps