customer has registered with no name or user name

hi,

I have a customer who has registered on my website - he has placed an order before.
he rang today to say that he'd forgotten his username and password, so I tried looking up his username. The strange thing is he doesn't actually have one - please see the attached screen shot.
now he wants to place more orders - is there some way to assign him a username? how is it possible that his account has been saved (and he's managed to place an order before) without having a name or username?

any help would be much appreciated.

kind regards,
Tanya

PLEASE IGNORE - i've just worked it out - I didn't have registration on my website when this customer last placed an order, so obviously when I bring him up on my customer list there is no username.
sorry for being daft!