Thank you so much for your suggestion here.
I was thinking of reformating the hard drive as some programs were taking
too long to execute. These included Office 2007 so I had to uninstall it.
I currently have it's 451 mg installation file therefore don't wish to begin
another download and install process as it takes quite long. Plus, I know I
won't be able to use much of the software after it expires so before it did,
I was thinking of doing few things and reformating the drive altogether.
I realize I can't bring Office back without the new trial installation.
I'm still kind of confused why all of a sudden it didn't work - all this
while didn't have any problems. And now that I'm left with it's product ID
missing, I'm not too sure how to contact Microsoft and/or to recover it and
have it working again.