My wife's XP has stopped booting up. We get a black screen with a live
mouse cursor, but no icons, task bar, or mouse menus. Only the black
screen and cursor.

Could someone suggest some steps to see some progress or to gauge what's
going on? If this were Unix/Linux, I'd know how to piece the filesystem
back together, piece by piece, but I don't even know how to find out how
to do so with windows.

I have explored the filesystem up and down from Linux, replaced the NTLD
file (or whatever) and some other files that I was able to get from
backups, but all resulting in no change.

Any ideas or help are appreciated,