Can’t connect my iphone to itunes

Can’t connect iphone to Itunes, you do not have permission. I had a problem with my iphone SE (1st edition) and had to reset it and restore it, but after i did the reset to factory i’ve erased it and then, when tryimg to connect to iTunes for restoring the backup i’ve made i get this message that i don’t have permission. I’ve tried all the things i’ve found on the net, but still the same error. What can i do about it?