Dear Karthik, the first thing is you need to change your photo and signature only if you received a notification at your registered Email or phone number asking you to change those details. If you haven't received any such notification, you needn't make any corrections and you can leave them the way they are right now. Login to your credentials and click on the button which says " Click here for corrections in the NEET 2019 Application". Make the necessary changes like updating the photo and signature accordingly. But if you are unable to make any changes ideally it is because you haven't received any notification and your images are good to go!

Hi Karthik, 

You can edit the form between 14th January to 31st January on the Application Correction Form provided. The link of the mentioned form is attached here. 

http://ntaneet.nic.in/Ntaneet/online/CandidateLogin.aspx

However, apart from the Photo and Signature, you cannot edit your Email ID, mobile number, medium of question paper and choice of examination centre. 

For you to be able to change your photo, the candidates will be notified about any issues/errors in their scanned images and signature through an SMS and email. And only those students should re-upload the correct images only if you receive such an sms/email. Otherwise you cannot. I am also attaching herewith the link to a website that will clearly guide you on the process. 

http://admission.aglasem.com/neet-2019-application-form-correction/#topbarnote

I hope this is useful.