You can contact through the numbers in the jeemain website

https://jeemain.nic.in/WebInfo/Public/View.aspx?page=78

Hi Mansi 

dont panic kindly once again check you application number if the problem persists then try to contact cbse as soon as possible

Dear Mansi,

If you are facing such problem again and again you can retrive your application number.

You can use below link to know your application number

https://jeemain.nic.in/JeeMainApp/Root/AccountRecovery.aspx

If still you face any problem you can contact to officials on Helpline No.: 7042399520, 7042399521, 7042399525 and 7042399526, between (10.00 AM to 5.30 PM) on working days

Good Luck!!

Hello Mansi
Please check multiple times that you are entering your correct application number. I would highly recommend contacting the JEE Main authorities as soon as possbile.
I'm posting the numbers of the official JEE Main helpine - 7042399520, 7042399521, 7042399525, 7042399526.
Address your issue to them and I'm sure it would be resolved.
All the best !