Iphone 3G NEED HELP WITH ERROR (1015)

Hey my girlfriend bought a second hand iphone 3g after he was jail breaked and alot of things she didnt want with it, so she tried to restored..
when i tried again this message has appeared on my screen "the iphone could not be restored. an unknown error occurred (1015)".
there is anything i can do to fix this problem or it is just a waste of time?
Thx in advance