i have iphone 3g and i have tried to restore it and itunes says error 1015. After that the iphone shows again icon that 'connect to itunes'. So what can i do? i have tried to switch off the computer, use different usb-port, reinstalling itunes..
that's kinda hard to say ,because i can't get iphone opened, it holds itself on the 'connect to itunes'-status. Can i check it anywhere else? and what for?
Have you restored using DFU method? Fair warning though unless it came from a Finnish carrier, if you manage to restore it would probably be locked to the carrier it originally came from and only they can unlock it so it might be unusable anyway.
how can i do restore in DFU mode? but iphone to DFU holding power and home-thing and then restore? yeah i tried it it didn't work 'cause it goes automaticly to the same as before
That's just to check that you entered DFU correctly. If so, then the only other thing you need to find out is if your friend hacked the phone by using the iPad baseband which is 6.15 whereas the iphone is 4.3. If he has you are probably stuck and will need to google baseband 6.15 as I can't really give further support on this site as putting the ipad firmware on an iphone is obviously not something apple designed or will support.