When reloading XP from an OEM disk, one usually invokes a program that
restores an image of the hard drive made by the PC maker as it was delivered
to you. This is different from a repair install of XP, which is supported
by the retail verison of XP. In a repair, only the windows files get
over-written. However, a repair will usually not fix registry problems,
since making a new default registry would lose all information about
installed programs.
While it is a little late to mention this, the system restore feature of XP
might have been able to fix the registry, by restoring it to a day or so
before the cleaner was used. XP restore points contain more than the
registry, but they do contain at least the registry. XP makes restore point
automatically, but you can always force a restore point to be created by
start --> help and support --> system restore --> create restore point.
It would have also been possible to manually restore the registry using the
XP recovery console run form the XP CD (if you have one) or form a
multi-floppy set (free download from Microsoft). See the following for
details on how to manually restore the XP registry:
http://www.pchell.com/support/recoverfromcorruptedregistry.shtml
As for any personal files that were on the PC, they are probably gone. The
act of restoring an image overwrites most of the hard drive. There is a
very small chance that some personal files were stored beyond the size of
the restored image, and their pattern of ones and zeros may be intact.
However, the index to them, the master file table (MFT), will have been
completely destroyed. Still, there are programs that can find files,
without using the MFT. These are in the general category called file
recovery programs or data recovery programs. For a list of many, some free,
try this link:
http://www.majorgeeks.com/downloads38.html
If you wish to try such a program, look for one that does not have to be
installed on the hard drive, since every write to the hard drive will
overwrite more of the old data. Some recovery programs can be run from a
bootable CD, that you write on a different PC, and some even come with a
bootable CD (Norton Utilities for exmple). When recovering files, be sure
NOT to write them to the internal hard drive, since that will overwrite more
of the old files. Use an external USB drive or a pen drive or similar.
For future reference, it would have been very easy to save copies of all
files, if you had not tried to do the OEM restore. Even if a PC is not
bootable into XP, it would be bootable from a CD that contains an operating
system. There are litterally dozens of free "live" CDs, meaning that they
will boot and run programs, but will not install on to the hard drive. My
favorite is KNOPPIX, which is a LINUX-based CD. KNOPIX is a big download,
about 700 Meg for the CD version. But, it will boot most PCs without extra
drivers, even PCs with SATA hard drives. It has a windows-like file manager
and can read from NTFS formatted drives, the default for XP. It can write
to external USB and firewire drives. It also comes with a full office
suite, a CD burner, etc. The DVD version, also free, comes with even more
programs. Link to KNOPPIX:
http://www.knopper.net/knoppix/index-en.html