Yarbles,
Since you kept your subscription up to date you should have no problem logging in!
You dont explain what the issue is,did you use your original log in name? Did you forget your PW?
If you look in the game folder you can find both the log in name and PW,I suggest everyone save a copy of this somewhere safe! Personally I have a copy saved in my drafts of an email account for quick references and also have a copy saved to a zip drive. I also store a copy of my settings folder,skins and gunsights,this make reinstalling the game simple and changing to a new comp almost painless!
YMMV.