Windows 8 Upgrading Windows from broken older version

Hi,

I have a genuine product key of Windows 7 but don't have its copy (DVD/ISO image). In this case, is it possible and lawful to install Windows 8 from a genuine copy of "Windows 8 Upgrade"? I don't want to buy the full version since it's a bit more expensive.

Thanks,
Culip

P.S. So here's the whole story: I purchased my laptop "Panasonic Japan Let'snote J10" in Japan. The laptop doesn't have an optical drive but it has "Windows 7 Japanese" and a "Windows recovery program (partition)" stored in its hard drive. And neither Windows 7 nor the recovery program works--but oddly enough, scandisk doesn't detect any error in the hard drive. Linux in the same hard drive has been working perfectly, which implies that the hardware is healthy.

Yes, it's legal to do so. Since your existing installation is not functional, I recommend that you do a clean install to make sure that any problems you are currently experiencing don't get propagated to the new install. Here's a link to help you do a clean install using the Win 8 upgrade media: http://lifehacker.com/5984278/how-to-do-a-clean-install-of-windows-8-with-an-upgrade-disc