Apologies for what may seem straightforward to those here, but was without computer for a whole month (after my XP got struck by lightning)... so having finally got my new Windows 7, I have to get my Norton's back. 
What seems to have occurred in the process is that the name (email address) on my original modem had to be used in order just to get online, and now - with 4 months left on my Norton's subscription with my most recent email address...it isn't accepting me to re-download on new computer.
(I have my Norton 'key' but can't get 'in' 'cos it isn't accepting my email address and password. May seem obvious to you, but I'm in a dither!).
Would very much appreciate any assistance.
Thankyou.