I cant update Iphone`s software
At first I tried to reset to factory settings, but this led to the fact that I was not allowed to activate the iPhone. Then I tried to restore it through iTunes, which was useless. I don't know what to do next
See the information in these support documents. Understand that the iPhone has to be eligible for an iOS update for it to update.
If your iPhone, iPad, or iPod touch won't update - Apple Support and this one, If you can't update or restore your iPhone or iPod touch - Apple Support