This is probably going to be kind of long, so sorry in advance!
My laptop has some pretty major issues. There's nothing I can really do about it right now, but I'm just working with what I have. So, a few months ago I decided to delete my WoW installation (which somehow involved manually deleting files, I'm not really sure why... I'm sure there was a good reason at the time) and my computer freaked out and deleted half of my installed programs, including all of my Sims games. They still showed up in the add/remove programs dialog, though, so I clicked "uninstall" on all of them, which caused my computer to complain about them being gone and remove them from the list. It also presumably deleted their uninstall files and registry entries, because those are gone. (I've already checked, so don't just point me to the manual uninstall page.)
Not having TS3 on my laptop didn't really bother me until now, so I didn't try to reinstall anything until yesterday. But, now my game doesn't work! I've only been trying to install and play the base game, none of my expansions, but it seems to think that the expansions are still there and crashes when they aren't there. The reason I think that that is the problem is because it doesn't seem to have an issue when I first install it (but I can't really play it that way because my CD got trapped in a dead computer years ago, so I use nraas nocd) but when I update, that's when it starts having issues (it displays an error on the launcher when I open it to test, as well) and every time I reinstall, it tells me that I still have expansions installed (but, of course, there's no option for "just delete whatever it is you're seeing").
I've already nuked all of my custom content, all of my store items, all of my saved games, in fact I've deleted every sims related file and registry entry I can find, other than HKEY_CURRENT_USER>Software>Electronic Arts>EA Core, since I don't know whether or not that's Sims related. Specifically, I've deleted HKEY_CURRENT_USER>Software>Electronic Arts>Sims 3 from the registry, the entire EA folder from My Documents, checked AppData, Program Files, and the Installshield folder for any stray files (there are none), even deleted the shortcuts from my desktop, reinstalled several times, and rebooted. Not necessarily in that order. (Any file deletion and registry editing happened after I uninstalled the game). It still doesn't work. I get a "Service Initialization Failed" error when I try to run the game directly, and some sort of "Error occurred during startup, check the log for more details" dialog when I start the launcher. I can post the log if you want, but it seems to just be system information, I can't find anything particularly related to whatever problem it's experiencing.
Please please please, if you have ANY idea what I can do to fix this, I'd be so grateful! I'm getting desperate here!