itunes says that my iphone is in recovery mode, but than i try restore, and it doesnt work…..please help?

im trying to restore my iphone 2g and every time i plug it in my it computer it says iphone is in restore mode, restore to use with itunes. , i start restoring, but than says an unknown error occured (2002) it has been (13) too and some other number at the end i dont know what that means the screen always shows a apple logo but than sometimes the usb cord and the itunes icon whenever i plug it in to restore, it starts to restore, but than in the middle shows that message again someone please help me out