Sims 3 won't launch after merging Origin accounts

Edit:  I just saw your new post, and that's great to hear.  I still think you'd want to do the following though, given the errors you've seen.

@MarLove6  The easiest way to address these issues is with a repair install.  First, go here:

https://www.microsoft.com/en-us/software-download/windows10

Download the Media Creation Tool, which will allow you to create an ISO of the latest Windows 10 build.  Proceed as if you're going to burn the ISO to disc, but when it's ready, close the MCT instead.  Then right-click on the ISO and select Mount; you'll now see it listed as its own drive in a File Explorer window.

From there, use this tutorial:

https://www.tenforums.com/tutorials/16397-repair-install-windows-10-place-upgrade.html

While this process should allow you to keep all your current user files, it's always best to back up anything essential beforehand, just in case.  If you don't see the prompt asking whether you want to keep personal files and folders (step 13), back out and try again.