Ok, I wasn't able to get to this until now.
Did all of that, I ended up with the.dll errors so I removed the folder to desktop, and my game opened. You are right none of my downloaded content is there. So does this mean there's a mod or a broken download from the Sims 3 store, or a save or something that is preventing my game from opening?
@poptart52 It's very unlikely that a save or Library item would prevent the game from loading at all because none of that data should be read until later in the loading process (saves) or perhaps not until you're in Edit Town (Library files). Store content is also unlikely to have any effect as long as you've installed it the legitimate way. However, downloads from the Exchange are third-party content, even though they're hosted by the Store site, and they can definitely cause issues once installed.
When Sims 3 won't launch at all, the problem is usually a mod or cc item, so I'd start there. Two somewhat common problems are having NRaas Cupcake without also having the Store bakery set installed (and loading properly), and having NRaas MasterController's Progression module present without both the MC and StoryProgression base mods. So please make sure neither is the case for you.
Once you've tested your mods and cc, you can start moving your other content from the old Sims 3 folder to the new one. Here's a description of everything in the user folder:
https://sims3.crinrict.com/en/2011/01/faq-user-files.html
Where the game will create a new file or folder, it's best to use that rather than the old version. That also goes for folders where you're transferring the files inside, for example move the contents of Library rather than the entire folder. You can probably just transfer your installed Store content: .ebc files in DCCache, ccmerged.package in DCBackup, files in Library and InstalledWorlds. But if you run into trouble again, try only moving the Sims3Packs in Downloads and reinstalling the Store content from scratch, a few items at a time.
Leave your saves for last, when you've sorted through everything else.
