Can I Ask forgiveness from Allah if I commit kufr unknowingly or I should be sure that I committed kufr for example O Allah forgive me I if I commit kufr unknowingly
Salaam, The fact that you did it unknowingly and want to ask for forgiveness, shows your strength in faith. There are so many ways you can ask for fogivness. You can make dikhr and recite astaghfirallah, you can make sure to repeat it in your daily prayers, and you can simply hold out your hands and make dua. Remember, that Allah (swt) is the oft-forgiving most-merciful. :) Hope that helps:) MuslimGap
Of course when you run to Allah and ask for his forgiveness and make tawbah and promise never to do it again Allah will forgive you and when you are worried this is a sign that you are a true believer. And remember this Allah loves it when you ask for forgiveness, or ask him something he loves it when you do this so remember that and never despair from Allahs mercy never ever think that way EVER.
And Allah knows best.
kufr. Check this out: islamiqate.com/3998/what-is-the-concept-of-kufr-in-quran. And, this will help you with understanding forgiveness if you want reference: islam.stackexchange.com/questions/28884/…