Help me get back to stock - ipod classic

[macguruil]

hello
I have received and ipod classic from my brother and it has dead for some time.
after i power it on i see that it has the rockbox utility and i want to get it back to stock.
after searching the forums i still cant put it to dfu mode so i can install with itunes the stock version.
after plugin it to the pc and pressing the menu select together i get some UMSbook - that i need to copy UBI file.
i just want to get back to stock

please help me

[Chronon]

Are you able to access Apple's Disk Mode?  Does that allow iTunes to recognize it?