My Vista Home Premium (SP2) is corrupted to near unusability. Proof?

1. I click the Firewall control panel and I get an error "Error loading
firewall.cpl. Firewall.cpl is not a valid win32 application" It sure is
not valid: when I go to C:\Windows\System32\Firewall.cpl, it shows a file
of ZERO bytes!

2. I try to click the Windows program installation/repair/removal control
panel, and the window blinks in and out.

It's been 28 months since this Vista installation has been in use, and
often rescued in ways that avoided a clean install entirely.

I think it is now time to do the clean install. For one thing, the 100 GB
Seagate drive (the one with the bootable Vista partition) after about two
years revealed 432 read errors with a region of the hard disk (discovered
by 'ddrescue' while using Ubuntu Linux), probably because the HP Pavilion
dv9500t like all HP notebooks is notorious for overheating, and this
failure to cool damages CPUs and shorten hard disk life.

MY PROBLEM: I am now living on the other side of the world. I made
recovery disks using HP's recovery manager, and I think the recovery
partition is deleted (not sure), but they were left with relatives on the
other side of the world (mistakenly). HP does not answer requests for how
to get recovery disks.

QUESTION: I have recovered the product key for the Vista installation
using product key recovery software (the Microsoft label on the bottom of
the computer is smudged beyond readability, not so for HP's label). Is
there a way to download Vista installation somehow and use my product key
to autheneticate the installation?