As an international student. I submitted my files through Netfile days ago, and I recently found that nonresident can not submit by Netfile. How can I fix it?

The first thing you should do is to contact the Canada Revenue Agency to verify that they did, in fact, receive your income tax return.  If they did receive it, there is no other action that you need to take.  The phone number is 1 800 959 8281.