hello dear,

Since you have lost your application form you need to contact the KCET authority as soon as possible because they are the only one who will give you a proper solution.

First of all please check your gmail inbox because while filling the form you had get one confirmation mail with registration number it will help you to find your application form and then try to contact the respective authority.

https://cetonline.karnataka.gov.in/kea/

Please visit the above link and scroll down there you will find several ways to contact them.

hope this will help you

all the best!!