Having had to do this a couple of times now, I've made myself a little handy list of the files to be copied from the old Sims folder to the new one, so as to avoid having to reinstall everything, avoid losing saved Sims, etc. I just wanted to share it where it might be found by people looking for this kind of information.
(BTW, I've been reading these forums for ages, since long before I even signed up for an account, IIRC. This is just the first time I've got anything to say that I thought was worth sharing
).
Folders:
Saves (this is your saved games; sometimes when doing this, I only copy the most recent games, knowing I can restore older backups later if I need to)
Mods (assuming you have mods, and as this is often a source of difficulty, you might want to reinstall selectively if you're trouble-shooting, etc.)
SavedSims (sims you've downloaded or created and saved to the bin)
InstalledWorlds (includes store worlds and custom content worlds; EP worlds are stored with the actual game install)
DCBackup (the ONLY thing in here you actually need is the
ccmerged.package; everything else can go if you need to save the space or just don't want to copy it over)
DCCache (this appears to be where the game stores all the information on your installed content, so if you copy this over, you don't have to reinstall it all)
Library (saved or downloaded lots, households, etc.)
Individual files (all found in the main root of The Sims 3 folder):
Options.ini (all your saved options such as volume, game options, windowed mode, etc. etc.)
userPresets.package (all your saved patterns, styles, and other such data)
As far as I can tell, and based on my own experimentation and stuff I've read around the web, that should restore all your content, saves, etc., and it still does generate the "factory reset" as far as I'm able to tell (even the install information, which surprised me).
I hope this is helpful. I seem to spend more time fixing things than I do playing the game.... *sigh*
