viktormikhail, never put an occupied lot into the bin. It corrupts your hood as soon as you do that.

Everything has been going fine, until I deleted the town and somehow four of my sims were still in there. I have no idea how this happened because I put them in a lot and moved them into a different town so I don't understand. I know there is no way to get them back, is there? Most likely not, I'm so upset. They were my main characters.

EDIT: I just remembered I have them on an external drive for the backup I did just 3 weeks ago. So how can I get them from the backup back onto the game so I can extract and clone?

Put your backup in and extract them from that. Simply copy paste your hood in. Unless it's a maxis hood in which case cut that first and put it on the desk top and put in your saved hood. Just make sure no two hoods have the same number. Part of what you can expect with corruption is vanishing sims.

When I did the backup, the hoods were already corrupted so I don't think I should put them back into my game.
In the backup how do I find the sims, since they all are named with those long numbers?

So I've got the same problem but this is like reading french to me. I downloaded simsPE but there's no tool option about neighbourhoods - do I have to extract something? I'm a complete technophobe so I'm worried I won't be able to do this. All I want is to move 5 sims in 3 households from one neighborhood to another, I've already corrupted that neighborhood by trying to move them out via the bin. Surely there must be a simpler way to do this? I don't care about what they are like, just what they look like, names, and family history if possible.

What they look like is the easiest:
https://pixel-trade.livejournal.com/16091.html - Tutorial on extracting, you'll want to follow this one, especially the Bodyshop parts!
https://fightocrime.livejournal.com/6410.html - This is for Mac, but has working pictures from SimPE, which can come in handy.

Remember to clone the sims in Bodyshop. If you package them, make sure you package the cloned sims, or CC won't be included. The clone will always be the newest in the catalog.

Also make sure to remove the files you extracted from SimPE from your Downloads or Savedsims folder when you're done in Bodyshop (before you go ingame), or they can cause problems. Only keep the cloned files generated by Bodyshop (the files with random numbers that pop up in SavedSims).

For the rest, you add the new sims via the sim bin in CAS and give them names, fix their personality, family history, relations, and anything else you can do in CAS.

Memories and other things like that is a bit more advanced and requires SimPE and a good tutorial.
Look here under "editing the inhabitants" depending on what you want to do. Personally I usually don't do anything beyond CAS with my sims.
https://ts2tutorialdatabase.tumblr.com/hood

But the thing that confuses me is these all require 'opening up neighborhoods in SimPE tools' but there is no neighborhood option for me. There isn't even anything on my computer called SimPE even though I downloaded it...

Which version did you download, and have you installed it? Just downloading isn't enough.

0.75.68 is most likely the one you want ifi you have the UC (68 is for M&G, 69 is optimized for a special pack Chris Hatch has). It comes as an installer version, and should do the trick if you're not too tech-savvy.

(I have 0.75f with the UC, but it has a few quirks. If you have the the game on discs, the 0.73.44-QA should work fine too)