Why is my sim card not working?

hello i want to ask about one thing, i have problems with my sim card in my iphone 7, well i recently restored my iphone and everything was working and i went to sleep and in the morning i saw my iphone restarted because it wanted code after restarting and after the restart my sim card doesnt work and iphone is telling me i need to update my phone, but i already instaled latest update. And i dont know what to do.