I now know the feeling of an aggravated, yet somber simmer whose mourning their corrupt file. Thanks moonshadow. I always thought a corrupt file was a deletion of a save via an action (reinstalling, cc, etc.). Let's all take a moment:
R.I.P Twinbrook-Shores save and Cast Members:
Feburary 2012 something- March 19, 2012. 8:03pm
I'm so sorry, Kirby!
My very first sims 3 file ever, my very first attempt at a legacy, (Before even the first Dreamer Legacy!) suffered from this problem. I suggest you do what I do to prevent this ever happening again, which is use the Save As button and save two files. For example, Save it as Twinbrook Shores, or whatever the title of your file is, then the next time you save, save it as Twinbrook Shores 2. Then, alternate between them each time you save. You can of course do more than 2, I just do 2 to save memory. This way, if one file gets corrupted, you have the other to rely on which was only dated one save ago!
Sadly, even this method isn't foolproof, because the corruption can actually spread super quick to the second file as well. That doesn't always happen, but sometimes it does. So, as well as doing the alternate saves, I reccomend that you constantly backup your saves. Say, every week or so. I actually am so paranoid about losing my legacy that I back them up every day I play.
So yea, what you do is copy the Saves folder in your Sims 3 folder, and paste it onto a memory stick or an empty CD drive.
If you want a quicker way to do it, just copy the saves folder and paste it somewhere other than your Sims 3 Folder. For example, I paste mine in the Documents. Backing them up every so often on something like a USB stick or an empty disk drive is still a good idea though because even if your computer fails or somehow gets broken, you will still have that save that you can then play on a new computer or whatever.
Finally, if you're not against mods, ErrorTrap by Twallan usually takes care of all these sorts of errors and corruptions.
I use literally all of these, I really suggest you do them too. Sorry if you already do these, by the way. You just didn't mention them so I felt it would be helpful to post.
Super long post, sorry, but I do hope it helps!