Friend lost his CD key
Yes, the key is not really needed to establish ownership of an account.
Your friend needs to contact support, top of the page and go from there.
That is, if the key was indeed used to create an account to begin with.
(edited by SandraSolace.7682)
Going forwad I would recommend your friend start keeping a list of keys and what they go to (I use a password app on my phone, has a section for serial keys for software).
And while they like to have it, like Sandra said, support generally doesn’t need it if you can supply enough other info.