Re: firefox problem.
Firefox stores all it's settings in it's profile the users Appdata folder (Local>Mozilla>Firefox>Profiles and Roaming>Mozilla>Firefox. Nothing easier than deleting these to 2 folders and start all over (except that they might be hidden, but that's a typical standard Windows thing, easy to change).
Most people don't backup that Appdata folder. So I assume your friend didn't either, especially not with a new first laptop and a program installed only yesterday. In that case she has to start from scratch and redo all addons, settings, passwords, bookmarks and such; but that won't be much.
So once this is solved it might be a good idea spend some time to set up a good backup strategy for her.