If you have forgotten your user ID and password both, then you will have to contact the administrators of KCET and generate new login credentials. Write an application to keauthority-ka@nic.in regarding change of login credentials. Provide all your details including ID, enrollment number, address. Do it as soon as possible.     

Hello candidate, please contact the required authorities regarding this matter and ask them regarding the same. Please visit this site to get their helpline number and email.

https://www.google.com/url?sa=t&source=web&rct=j&url=http://kea.kar.nic.in/cet_2019.htm&ved=2ahUKEwi2ovXN8vniAhXUfH0KHe4fC2cQFjAKegQICBAB&usg=AOvVaw2zSh4LBM6A2MmYGze0Q1_0

Hope this helps you.