How to fix mobile network not available J510F nougta

Hello friends

I try to solve this problem but I cant.On th ephone appear the networks but when I try to call it appear MObile network not available and when I try to search manualy for nwtworks it appear error while searching network.
Android its 7.1.1 .I dont reflash the phone only I reset,but same story.
So have anyone some ideas?Thanks brothers