@dmacay95 I haven't experimented enough with swapping around the files within the save folder to be sure exactly what information is stored in each. (Some of it is obvious, but not all.) But the .nhd file is the big one, other than TravelDB if your sims travel a lot. So I would imagine that most of the data you want to preserve is in there, unfortunately. If you can't find some working combination of files that includes the .nhd, you might not be able to recover the save.
Just in case you didn't know, the sims you create in-game are also saved to Library when you exit CAS, as are any lots you save after building them. Anything that has an entry in the in-game bin you see in Edit Town also has a Library entry. The sims there won't have progressed though—they'll be the same clean slates they were when they came out of CAS.
The save-preserving mods are all from NRaas.
- ErrorTrap and Overwatch work together to clean up errors, corrupt data, and stuck sims. ErrorTrap is the only core mod on this list; be sure to get the version that corresponds to your type of install (Origin/Steam/disc).
- MasterController loads a very long list of commands for you to run. The most useful for the health of your saves are the ones to reset sims, objects, lots, or the whole town at once.
- Traveler replaces the broken travel transition with its own and makes errors much less likely.
- Register controls the Service (maids, repairpeople, burglars, etc.) and Role (assigned to role-giving objects, like cash registers) sims. You may or may not need it, but it's very helpful if you notice issues with either type of sim.
- Traffic prevents the unnecessary excess spawning of vehicles. If Overwatch is reporting on hundreds or thousands of vehicles cleaned up every night, or your town is overwhelmed by ice cream trucks, Traffic will shut that all down.
All of these mods work just fine on default settings, so you can drop them in your game folder and not pay too much attention. ErrorTrap in particular creates a lot of reports, both in-game notifications and scripterrors in your game folder, but those are mostly just it doing its job; there's no reason to worry unless you're having issues with your save. In that case, you can take the scripterrors to NRaas and ask that someone read them for you. The people there are very friendly and helpful, and someone will let you know what's going on, and what needs to be fixed.