Hey Rohit,

It would be really helpful if you have provided the name of the exam form you applied for which forget the user id. Comment below so I can help you better. But in general, you can find two option below the login page. one is Forget Password and another one is Forget Username. In both cases, there will be a process which let you confirm that you are the real user by sending you OTP or link in your registered email id. This will let you change the login information.

In many case, they send you the details to your email id after you filled the form. I suggest you check your email id once. And if didn't work then contact the examination authority they will help you for sure.

Hope that helps

all the best