I did broked it, but I fixed it in SimPE. Still, the picture is kind of funny, in a sick way, so I thought I'd share.
I had to delete a custom bed that was "stuck" - flashing blue - and in the process I deleted the Sim standing next to it, a child (girl). I've done it before, no problem, so I exited the lot, came back in... and she was floating in the air by her mom. When the mom was finally able to put her down the kid lay on the ground like a quadriplegic. She was a baby but in a kid body.
Yes, you can imagine the sick jokes circulating around our living room last night.
Growing her up didn't work because, I think, the Sims couldn't pick her up. It finally occurred to me that if I could find her file in SimPE I might be able to change her age and, sure enough, after some poking I found it. I made her a toddler just because I was scared to death my game was going to self destruct because I dared to touch neighbourhood files without knowing what I was doing, and she showed up at the mailbox, still in her child body, but now with toddler interactions. THEN I was able to finally grow her up.
(My kids were all for letting her continue as a toddler in the child body just to see what would happen but alas I am not as adventurous as they are...)