This utility by Mootilda seems to be unsupported. For ME, it's not working. I've read everything I can find and the only things I can find is that .NET framework 2 is required, and clicking 'versioned backup" does nothing. I run it, clicking "remove", and "yes" to the pop-up asking if I have a backup (since it won't go forward without that answer). A list of stuff shows: no character files, invalid relationship, etc. I expected that when I run it again most of those things would be removed - but there is no change, like it didn't DO anything. I know it doesn't remove everything, and while I don't know what it does NOT remove, it should have removed SOMETHING.

.NET Framework 4 came with Win10. If you have anything later than Win7, you already have the requisite thing installed. As I remember it (and I don't really use the Hoodchecker), the way it works is a little counterintuitive. Perhaps you could list exactly what you are doing?

I don't have Windows10, I have 7. But Hood Checker requires Net 2, not 4, and I have 2.; I can run SimPE, lot adjuster, HCDU, CPack Editor - I think they require 2. also.
Running hood checker is not complicated: run exec./start/ pick hood/next/ click REMOVE/"Yes" to pop up about backups (it won't continue if you don't say yes)/click finish.

after selecting the neighborhood there would be 2 buttons; "Check", "Remove". "Check" would list things that need to be fixed. "Remove" would attempt to fix the neighborhood; things not fixed would be listed.

If you didn't have the required .net it wouldn't even begin so that's definitely not a problem.
It doesn't remove everything, no character files will occur for those NPCs that are in the download folder so you wouldn't want it to try to fix that. There is several conditions that it can't fix memories or invalid relationships for (and I don't recall what they all are).

I have the source code and an updated version for A&N (which doesn't see sim's relationship with self as invalid as those are necessary to prevent 'met self' memories) so I can offer limited support.

I can see that relation issues ARE removed. And sounds like "no character files" is OK - even though I don't know what you mean by "NPCs in the download folder".
So my issue is resolved. Thanks.

If you download a mod that contains NPCs - Multi PT mods, some animated animals, etc - you'll have NPC character files in your download folder. Recent mods will point out if they contain NPCs, but older ones may not. HoodChecker only checks your neighborhood folder, so it won't notice the character data is in your download folder and give you that error message. As long as you have the same amount of missing character files in every neighborhood, no need to worry.

I have one of those No Character File in most of my hoods. I have identified it as Beck's Bigwheel for toddlers. In my medieval hood I have dozens of No Character Files because I have a lot of her animated animals. It gave me palpitations the first time I saw that in Hoodchecker. I always run Hoodchecker on Check first than Remove the second round so I can see what was removed and save a copy both times.

You can always ignore the no character file and consider it to be just advise. Whenever your game runs any sim without a character file is removed (which does cause big problems) so if Hoodchecker can't find a character file then it is definitely in your download folder, it can't actually be missing. It is because of the extra built in NPCs in A&N that I had to update it for A&N.

Chris, if it's not safe to let Hoodchecker remove the missing character files, is there a way to run it selectively? There doesn't appear to be. If it's seeing a sims relationship with itself as invalid and it shouldn't be, or removing NPC character files that should not be removed, can those character files be restored after running the program?

It can't 'remove' selectively. Hood checker doesn't try to fix missing character files so you don't need to worry about that. Surprisingly it does already have an option to treat relationships with self as valid but that option is set to never show, for A&N I just set the default for that option as on.
It does need a bit of an update which I do have and can post easily enough, however the GNU licence requires the source be available and I've been too busy (lazy) to sort that out.