This has happened to me several times, if the resetting doesn't work almost immediately, I usually try to copy the family/house in edit town mode. You don't have to replace them or anything, but the action of copying resets the actions of everyone (in your household) in town. That typically resets everything BUT ... if the save game is corrupted, which is usually the case if resetting doesn't work, you might not be able to get into edit town mode, the main frame of the game will disappear and you will be able to move the camera around almost like making a movie. If that is the case, you might be better off going to the backed up save game.
When this happens this badly to me, before I try going back a save game, I look around the town and find clustered Sims around entrances and attempt to reset all of them first, it works about 1 in 5 times, but might be worth the attempt depending on how long ago your last save game is.
If I could suggest, After getting into the old save game, if you have to use it, make a copy of the household right away, you could even try starting a new game and replacing the household, as what corrupted the game may happen again anyways.
I am by no means an expert on troubleshooting this game, but this is what has worked for me, If someone has a better suggestion I would also be interrested as I have 2 or 3 that are just so corrupted that I can't even play them anymore.
This only usually happens to me when I either have age turned off or at extreme length and the town starts to get very congested, plenty of new kids with no elders passing on, and happens around week 10-12. The whole thing is so much worse now with all the paparazzi running around.