I have sent my application by mail, not online, but still able to check my status online. you can also do it, here are the steps.
When you gave paper application you must have provided in it an email address, suppose email is 123 @ abc.xyz
Now you have gotten file number, but you can not check your status in online
sinp portal by file number, you must have a username and password.
How to get a username and password, here are steps
Go to
SINP Online portal Website
Select Registration,
Provide your details as asked and write your email address the same that you have given in paper application i.e 123 @ abc.xyz
write username of your choice and click submit.
you will receive email from SINP regarding registration.
Mine registration took 3 days to be active.
(
Note: you must have to register with the same email that you have provided them for correspondence)
Hope it helps