Please read the details first. I've tried looking up the issue I'm having to no avail--if this has been solved please feel free to delete this and direct me in the right direction.
I play the Sims 3 on a Mac. Recently the game updated and then my computer software updated to a new OS. Before the OS update I noticed I couldn't access my saved games, CC, or anything. Nothing in my Documents>Electronic Arts>The Sims 3 showed up in the launcher or in game. I backed up my games and tried to reset by deleting the Sims 3 folder and restarting the game (a process that always worked before). Usually it would respawn a new folder; this time it didn't. I started a new game and still, no folder in documents. That new game is still working now but I can't figure out how to gain access to my old saved games. I can't even find the file for the new game. I have everything backed up. How can I gain access to my old games? Is there a new location I should be searching for? I've tried everything I know.

If you have everything backed up, try copying and pasting the backed up files into the folder (just the files that you are missing). Make sure you then clear the cache folder and try again

I've read it quite often that sometimes the Mac version suddenly creates the user folder in the weirdest locations, usually within the application folder itself. I'd start with a file search first, using a file or folder name that is particular to The Sims, like InstalledWorlds or CustomMusic or .nhd.
I don't know how your search function in MacOs is configured but you'd probably have to add hidden files to the search filters and search for file names and not file contents.
If this doesn't yield any results try to right-click on the The Sims application in Applications and choose "Show Package Contents". This should open the application folder and sometimes the user folder has ended up there, even though it shouldn't. It could also have a weird name like "%USERNAME/My Documents/ElectronicArts/TheSims" or somesuch.

I've searched the application folder and still can't find it. I can't even find the new games I've started. Are there any other ideas? In all my years of playing The Sims on Mac and Windows I've never had this happen. It's pretty frustrating.