How to boot into previous installation?

I had a bit of a disaster trying to recover some space on my laptop be
deleting a 7Gb partition. This went wrong and as a result windows would not
boot. I reinstalled windows on what I believed to be the 7Gb partition. I
now have a 7Gb D drive with a 'windows' folder on it and a 50Gb C drive with
a 'windows' folder and a 'windows.0' folder. Boot.ini suggests it is booting
from 'windows.0' How can I get it to boot to my previous installation which
is in the C:\windows directory? I have tried editing boot.ini to change
windows.0 to windows but it fails to boot and I have to go through the
installation routine again.

TIA

Jon