No simcard error and mobile network option is missing from settings

[Betty Elisavet]

Hi,

Me and my husband were on vacation, our phones are unlocked. He has a GS7 and I have a GS6 edge. We put back our old simcards and now we have an error that no simcard registered and the mobile network option is missing in settings.

I don't know what to do and my network provider doesn't know either.

Please help!