Character data has gone AWOL

I had to pick the worst time of year to have something go wrong. Still, it's a pretty bizarre one. Bear with me, I've put down everything I remember doing today because I have no idea what caused this or what to do. Sorry for the length and rambling.

I last played (all EPs, no stuff packs) a week ago, I've been playing Pets for a while and aside from a stuck cat pregnancy and the you-can't-move-in-your girlfriend-because-she-counts-as-a-pet bug I've had no problems. Since I had glorious nothing to do today, I downloaded some clothes (doing my part to destroy paysites while my housemates aren't here) and a couple of Awesome^TM tweaks. Nothing big - enemiesaccumulate, dailygardener, things like that. I made myself a new set of default replacement eyes. I booted up Bodyshop a few times to check that the eyes were how I wanted and that I had the right meshes. One of the sims I was using to check the eyes was a CAS sim, currently a teenager, who I exported because I wasn't happy with how he was aging. I couldn't swear it, but I'm pretty sure that that's not what his face looked like when I made him. (He started as a toddler, but I tweaked his adult face until he was good and pretty in CAS before setting him back to toddler. Somewhere the pretty got lost.) Anyway, there are two versions of him in Bodyshop, the original export and the clone that I've tweaked. At this point, both of them looked exactly as they should.

I continued on with my downloading spree, looted some Chic gear from PMBD and downloaded the shiny new Pets edition of the Kitten Killer. (Yes, I know, please keep reading.) After deleting some eyes and skins I had never used and hacks that I know conflict, I did unzip InTeen and my new clothes into the correct folders. But as soon as those had unzipped I shut my computer down, plugged my secondary hard drive back in and backed up the entire Sims 2 folder. I didn't start the game or Bodyshop before I backed up so the files were in there, but none of them had been used.

After backing up I opened Bodyshop to check the new clothes, but when the saved sims folder opened up both the clone I fixed and the original export suddenly had white faces/heads except for the eyes and hair. I do have default replacements in, so I opened one up and tried changing the skin tone to one I know is in perfect working order. The rest of his body changed tone, but the face stayed white whether I used one of the custom default tones or a straight custom one. I can put full-face makeup onto the white, which was briefly entertaining. Still, I figured I'd just re-export him and pretty him up again. But when I open up SimSurgery in SimPE, he's not available. He's still listed in the Sim Browser but it says he has no character data.

So I kill it, copy over the backup, put the skintone I deleted back in just in case (even though he's got Maxis-default DNA) and take InTeen out.

The backup showed identical size and modification date (19th December), and still shows no character data. But the last time I played I was playing his house and he was fine. And he does still seem to have DNA, relationships, skills all that sort of thing. Unfortunately the last backup I have before this one is from when I installed Pets, and he was still a child then. Is there a way I can repair the character data or am I going to have to roll the whole neighbourhood back almost two months?

Because that would make me cry. And burn the whole neighbourhood to the ground then start over, because I'm vindictive.