mobile network not working /cant add apn (access point names)

I figured problem with my friend Priv that he cant use mobile network, when i checked the apn setting i saw its empty after while search i found three different answers :
1-factory reset ! actually it was not the solution
2-remove and add Sim card ! its worked but temporary until first restart
3-frimware update ! not effect anything
so if enyone khow about this issue please help to find out a way to fix it
many thanks

Download from this link