I really messed up my sims game, please help

Oh no, that sounds terrible, I'm so sorry! 😞 With all the work players put into a save it can be so devastating to lose one or have one messed up.

With no cc or mods, have you tried repairing your game and tried creating a new save to see what the sims and Newcrest look like? If they are both okay then add one mod back in at a time, same with the cc. I know it sounds painful to do but the sims can be so sensitive to cc and mods.

Another alternative, but might be your last resort, is to create a brand new sims 4 folder. I do this if I feel like my current folder is just getting too glitchy and I want to start fresh. Of course then I have to redownload everything, but sometimes it's worth it if your game is just not enjoyable to play. Unfortunately though, this will not assist with getting your saves back to where they were.

I do hope you are able to find a solution, good luck!

@kaiitouu  Please start by looking for newer saves.  It's probably easiest to just search your computer:  Open a File Explorer window, click This PC in the left panel, and enter Slot_ in the search field in the upper-right corner.  For any save you find, you can click on its name and then click the "Open file location" button in the menu.

If you use OneDrive at all, it's also worth looking there for any stray saves or other Sims 4 content, e.g. Tray files.

You can proceed however you want from here, but if you have a number of saves scattered around, I'd suggest creating a folder on your desktop called "extra saves" or similar, then moving all the saves you can find to that folder.  From there, you can check the modified dates on the files and find the newest copies, then move those to Documents > Electronic Arts > The Sims 4 > saves and see whether the game will load them.

If a save won't load, make sure it's named properly.  A save needs to have the format Slot_xxxxxxxx.save , where the Xs stand in for an eight-digit hexidecimal (base 16) number.  So the number can be 00000002 or 00000016 or similar, but it needs to be exactly eight digits long, with no extra characters.  And the file needs to end in .save with nothing after it.

If you do find a recent save and your sims aren't wearing any of their custom content, don't save your progress; just come back to it later when all your cc is added back.  If you previously saved with the cc missing, you can look for a slightly older file, perhaps one with the same number but with a .verx ending, that's just an older version of the same save, and you can try loading that instead.  The .ver0 file will be the newest among the backups and the .ver4 the oldest.

Hopefully you'll be able to find at least one save with your data intact, or most of it.  If you have to add back the cc, that can be tedious, but it's better than losing the save entirely.  And in the future, it's a good idea to back up your saves, or perhaps the entire saves folder, periodically and especially before any game update.  That way, you'll never be in danger of losing all your progress.