Before playing The Sims 2 I went on the Body Shop and used it for a little while. After I started up the game when I got to the blue loading screen it said "Creating Pets" as if I had just installed the Pets expansion pack even though I already had it installed for a long time. So when I got to the neighborhood (Pleasantview) I noticed that the Dreamer household wasn't there, even though the house was still present. I also tried moving in a household which had 3 members in it but once I moved them in there was only 1 member. I'm not sure whether it's because of the custom content I own or because I forgot to turn off a cheat but it's really strange . . .

Edit: I went back to the game and another household vanished!

Edit #2: I also wanted to add that when I moved the household with 3 members in the lots name was changed to AAA. I was wondering if this could mean something . . .

My guess is that something is seriously wrong with your game. Try running a completely vanilla game and see if that happens again, otherwise you might be looking at a reinstall.

Okay, so I reinstalled the game, and nothing seems to be wrong so far even though the families that disappeared still aren't there. I know this sounds dumb, but do you think there's a way to get them back even though I didn't create a backup?

Are you using disks or the UC? Reinstalling is always the last thing to do and only for corrupt installation files which it not normally is. You are probably giving yourself unneeded work. Vanishing sims is most commonly a sign of advanced neighbourhood corruption found in the files under Documents and nothing to do with your installation files on C drive.

If you reinstalled you wiped everything and now have a new game, so no nothing will be there. If you ever want to keep anything that requires backed up files.

Do you know about all the things that cause corruption?
Do you have all essential mods?
Are you fully patched?

I'm using disks. When I reinstalled the game all my old data was still there just the sims who disappeared didn't come back. I know that certain mods and forgetting to turn off certain cheats can cause game corruption. Most of the mods I have are just slight changes to the game such as custom items and slight adjustments to gameplay, so not really essential I suppose. By fully patched, do you mean fully updated or have all expansion packs? The only expansion packs I have are Nightlife, University and Pets, my ep's are fully updated. Sorry if the way I explained it is a bit confusing. :/

That is not a good sign, nothing of your past game should have been there. it should be just like you bought the game off the shelf. I think now you will need to uninstall and make sure all files are completely gone. http://modthesims.info/wiki.php?tit..._Help:Uninstall Don't rush to reinstall for issues since it's rarely the answer and uninstalling can leave behind files and then when you reinstall give issues. Most times issues are related to cc which are small issues normally rectified by finding and removing the cc or it's corruption. Corruption can be slowed down by using Hood Checker and making frequent backups.

Mods and cheats don't normally cause corruption, but practices such as deleting sims from the bin, moving sims between hoods, deleting graves those will cause instant corruption. All the hoods as shipped by the game already come with a certain amount of corruption so if you want to play those long term we recommend installing clean templates.
Corruption: http://simswiki.info/wiki.php%3Ftit...Hood_Corruption
Essential mods are to help prevent hood and game corruption most are listed on that page. Not shown are No Sim Loaded http://www.leefish.nl/mybb/thread-1665.html that also requires Smarter EP check as mentioned in the mods details.
No patches are fixes EA made that need to be applied to each EP and SP you have installed. http://modthesims.info/wiki.php?tit...elp:TS2_Patches

If she chose to save her game data during the uninstall process, her old Sims would still be there when she reinstalled. It's been a long time since I've uninstalled, but I remember it asking if you want to remove everything or if you want to keep the stuff in Documents. But anyway that neighborhood with missing Sims is damaged beyond repair. The Sims who are missing are most likely gone for good and others will start disappearing if you continue to play that hood. It's best to either start fresh with a brand new hood or to salvage what you can by packaging up any Sims and lots that you want to keep and moving them into a clean hood.

http://simswiki.info/Game_Help:Moving_Sims

Oops, I should've mentioned that I saved my game data during the uninstall process, that's why the data is still there. Other than that, I'll do what I can to prevent the neighborhood from any further damage or corruption (and just recreate new sims), thanks for the suggestions! That was a bit short but I think everything should be fine for now.

I agree with what was said by Jo's when you have problem like that I think it is best to just uninstall the whole game and start from the bottom up ( fresh ) as if you have just purchase the game.
When I first started playing the Sims I did things I did not know not to do like controlling Mrs, Crumplebottom , soon there after my game became corrupt right away.

Sims would walk pass a Sims house with furniture attached to there head, even the mail carrier it happen to.
Thanks to the Sims community and here on MTS I learn fast about what not to do, I always go back often and read about what causes corruption so I won't forget and stay on top of it.