Okay, let's try a variety of things:
ResetSim:
- Open cheat console (shift, ctrl, c)
- type in: resetSim firstname surname
- hit enter
That probably won't work, but give it a try all the same.
Move him in and out:
- go to edit town
- click on your household and choose split household (he should be there, otherwise, try merge household)
- move the guy out / in with someone else
- Resume live mode and play for a bit
- Move him back in via edit town
Also look here: http://answers.ea.com/t5/The-Sims-3/ISSUE-Savegame-Corruption/td-p/968290
