Where has my SATA drive gone?

Hi guys

I have XP installed on one sata drive.
And I have a second drive, partitioned, for games and for data
And I have a third drive, in a removeable sata caddy.

A friend rang and asked me how to use XP CD to use XP restore, and I couldn't remember, so booted off my own XP disk to recall and the XP disk booted, but then, rebooted my PC without an option of any sort.

I never got as far as XP instalation.

I now have no partitioned drive, so have no games and no data :(

What's gone wrong, and how on earth did that happen? The drive is showing in BIOS and in disk management, but not recognised by XP, so maybe it's lost its file tabes or summit?

I dunno...at a loss. Any ideas chaps? I'm gutted.... most of it is backed up, but what a palaver, and all for something I dont know the reason for :(